Method of energy conversion

ABSTRACT

The present invention provides an energy conversion composition which has an excellent capability of absorbing and damping energy such as dynamic, thermal, or electric energy. The composition can be made into a very thin and small but excellent damping product. The energy conversion composition is characterized in that its base material contains a moment activator which can increase the amount of dipole moments in the base material. The energy conversion composition can be utilized as a vibration damping, sound absorptive, impact absorptive, vibration-proof, electromagnetic wave absorptive, piezoelectric, and endothermal material as well as a polarity liquid.

CROSS REFERENCE TO RELATED APPLICATION

[0001] This application is a divisional of U.S. Application Ser. No.09/091,563, filed on Mar. 22, 1999, which is incorporated herein in itsentirety.

TECHNICAL FIELD

[0002] The present invention generally relates to energy conversioncompositions, excluding conversion of electrical energy into mechanicalenergy, which can effectively absorb and damp energy such as dynamic,thermal, and/or electrical energy excluding optical energy.

BACKGROUND ART

[0003] There conventionally exists a vibration energy damping materialof a soft vinyl chloride resin and a plasticizer.

[0004] Such a soft vinyl chloride resin can damp vibration energy on thesurface of and/or within the resin by converting the vibration energyinto frictional heat, only to a very limited extent.

[0005] Japanese Laid-Open Patent Publication No. 5-332047 discloses aliquid material which absorbs or damps vibration energy to a degree.This liquid material or a viscous fluid comprises a glycol as a chiefingredient. Vibration energy or seismic energy generates an electricfield in the viscous fluid and changes the viscosity of the fluid, anattempt to efficiently damp the dynamic energy.

[0006] A very large amount of liquid material is required to effectivelydamp huge seismic energy, for instance, from a major earthquake. Due togradual oxidization of the liquid material, its damping performance getslowered over time, requiring periodical refreshment of the liquidmaterial. Accordingly, there exists a strong demand for a vibrationdamping material which with a minimum amount can efficiently dampseismic energy or vibrations over a longer period of time without suchrefreshment.

[0007] A sound or noise absorptive or damping material containing glasswool is known. Glass wool can damp sound or noise by consuming theenergy as frictional heat when sound collides with the surface of glasswool fibers and passes therethrough.

[0008] The glass wool type sound absorptive material, however, need beprepared relatively thick to provide sufficient sound absorption. Thematerial cannot effectively absorb sound of a low frequency below 1,000Hz. The material does not function well at a frequency below 500 Hz.

[0009] There is an impact absorptive or damping material. JapanesePatent Laid-Open Publication No. 6-300071 discloses an impact absorptivematerial which comprises short fibers dispersed in a foamed polymer.This impact absorptive material can damp an impact applied against asurface portion of the formed material through the gradual collapse ofthe structural integration of the formed material. The short fibersdispersed in the foamed material act as a physical binder to promote thetensile strength of the material and prevent its cracking.

[0010] This impact absorptive material, however, requires a considerablethickness and volume to provide sufficient impact damping. Accordingly,if there is no sufficient room for installment, this impact absorptivematerial cannot be conveniently utilized.

[0011] There is an electromagnetic shield material as proposed inJapanese Patent Laid-Open Publication No. 5-255521, which can absorbelectromagnetic energy to an extent. This material comprises anultraviolet absorptive compound capable of absorbing or dampingultraviolet rays of a wavelength of 250 to 400 nm through excitation ofthe molecules of the compound and conversion of the ray energy intothermal energy.

[0012] This material need be 10 to 20 mm thick to provide a sufficientabsorption of ultraviolet rays. Such a thick sheet hinders visibility. Ademand for a material which can provide a thin but effectiveelectromagnetic shield is strong.

[0013] Butyl rubber or NBR is conventionally utilized to provide avibration damping material. Such a rubber material is economical andeasy to process as well as possesses a considerable mechanical strength.

[0014] Such a rubber material shows an excelled vibration dampingproperty among polymers, however, if a rubber material is used singly,its damping ability is somehow limited. Therefore, a metal plate or coreor oil damper is conventionally incorporated in a rubber-type vibrationdamping material, which is rather complicated and costly to manufacture.

[0015] Accordingly, there is a strong demand for a vibration dampingmaterial which itself can provide excellent vibration absorption ordamping.

[0016] Japanese Patent Laid-Open Publication No. 5-5215 discloses anendothermic fiber material. This material is a polymer comprising astraight-chain aliphatic carboxylic acid and straight-chain aliphaticdiol, such as polyethyleneadipate, polypentamethyleneadipate, orpolytetramethynenglutarate. The polymer absorbs heat as it melts andprovides heat damping, though, a large amount of polymer is required toprovide sufficient heat absorption.

[0017] A viscous fluid mainly composed of a glycol provides a highlatent heat medium to be used as a transmission cooler, engine coolantor mold cooler. The cooling property of the fluid is given by thefollowing equation.

(ΔH−RT)/V=(SP)²

[0018] ΔH: latent heat, SP: SP value (solubility parameter). The SPvalue is an indication of polarity and increases as dipoles increase.Water has the largest SP value, however, use of water is not practicalbecause water tends to corrode metals. Glycol has an excellent rustinhibition property, however, glycol does not provide a high latent heatproperty.

[0019] As described above, conventional energy conversion (damping)materials or compositions have insufficient damping capabilities, orrequire a considerable thickness or volume to provide a satisfactorydamping capability.

[0020] The inventors have discovered through a lengthy research onenergy conversion compositions that the magnitude of dipole moment ofthe compositions is directly related to their energyabsorption/conversion/damping capability.

[0021] The inventors have also found that the dielectric loss factor ofthe compositions is related with their energy absorption/conversiondamping capability.

[0022] Accordingly, an object of the present invention is to provide anenergy conversion composition, excluding conversion of electrical energyinto mechanical energy, which has an excellently improved capability ofabsorbing/converting or damping energy such as dynamic, thermal, and/orelectric energy excluding optical energy. Another object, of the presentinvention is to provide an energy conversion/damping composition whichcan provide an excellently improved ability with a minimal thickness orvolume.

DISCLOSURE OF THE INVENTION

[0023] An energy conversion composition according to this invention canbe prepared into, but not limited to, an unconstrained or constrainedvibration damping sheet, paint, paper, asphalt material (for automobileflooring), or a vibration damping material for asphalt roads (noiselessroads), or sound or noise absorptive material for sound absorptivesheets, fibers, foam materials, films or molds, or impact absorptivematerial for training shoe soles, protections, head gears, plastercasts, mats, supporters, handle grips and saddles of bicycles ormotorbikes, front forks, grip ends of tennis or badminton rackets,baseball bats, or golf clubs, grip tapes, hammer grips, slippers, gunbottoms, shoulder pads, or bulletproof jackets, or vibration-proofrubber material for earthquake damping rubbers or molds, orelectromagnetic shield material for X-ray or ultraviolet shield sheets,or piezoelectric material (excluding ones that convert electrical energyto mechanical energy), or endothermic material for endothermic fibers orpellets, or viscous fluid for earthquake damping apparatus, or polarityliquid for engine mount liquids, shock absorber oils, power supplytransmission cooling liquids, engine coolants, floor heater media orsolar heat media.

[0024] The energy conversion composition according to this invention ischaracterized in that its base material contains a moment promoter ormoment activator which increases or promotes the amount or magnitude ofdipole moment in the base material.

[0025] Such a base material is not limited to but may be a polymermaterial such as polyvinyl chloride, polyethylene, polypropylene,ethylene-vinyl acetate copolymer, polymethyl methacrylate,polyvinylidene fluoride, polyisoprene, polystyrene,styrene-butadiene-acrylonitrile copolymer, styrene-acrylonitrilecopolymer, acrylonitrile-butadiene rubber (NBR), styrene-butadienerubber (SBR), butadiene rubber (BR), natural rubber (NR), isoprenerubber (IR), or their selected mixture, among which polyvinyl chlorideis preferred for its workability and low cost.

[0026] When such an energy conversion composition is to be made into anoise or impact absorptive material, electromagnetic shield material,endothermic material, or polarity material, its base material may beadditionally provided with polyester, polyurethane, polyamide,polyvinylidene, polyacrylonitrile, polyvinylalcohol, or cellulose. Inparticular, when the composition is to be made into a sound absorptivematerial, a foaming agent may be added to provide a porous material toimprove sound damping.

[0027] When the composition is to be made into a vibration dampingrubber material, the base material may be acrylonitrile-butadiene rubber(NBR), styrene-butadiene rubber (SBR), butadiene rubber (BR), naturalrubber (NR), or isoprene rubber (IR). When a polarity liquid is to beprovided, the base material may be a glycol or water.

[0028] Mica scales, glass pieces, carbon fibers, calcium carbonate,barite, precipitated barium sulfate, corrosion inhibitor, dye,antioxidant, electricity control agent, stabilizer, or wetting agent maybe selectively added to the base material as desired.

[0029] When vibration, sound, impact, electricity, pressure, or heatenergy is applied onto the base material, dipoles 12 in the basematerial 11 as shown FIG. 1 are displaced to a state such as shown inFIG. 2. This displacement of the dipoles 12 may be caused by rotation orshifting of phase within the base material 11.

[0030] Prior to application of energy, the dipoles 12 in the basematerial 11 as shown in FIG. 1 are stable. When an energy is appliedonto the base material, the dipoles 12 in the base material 11 aredisplaced into an unstable state. They are then prompted to return to astable state such as shown in FIG. 1.

[0031] The applied energy is effectively consumed through this process.It is assumed that the consumption of energy provided by thedisplacement and recovery of the dipoles provides noise, impact,vibration, electromagnetic wave, or heat damping.

[0032] The mechanism of energy absorption/damping is associated with themagnitude of dipole moment in the base material 11. When the magnitudeof dipole moment in the base material 11 is large, the base material 11possesses a high energy absorptive capability.

[0033] The magnitude of dipole moment in the base material is subject tothe base material used. Even when the base material is the same, themagnitude of dipole moment to be provided in the base material varieswith the working temperature. The magnitude of dipole moment is alsoaffected by the type and magnitude of particular energy applied onto thebase material. Thus, the base material should be selected so as toprovide the largest possible magnitude of dipole moment, considering thepossible or expected working temperature as well as the type andmagnitude of the energy to be applied.

[0034] It is desirable to also take into consideration factors such asworkability, availability, temperature characteristics (temperatureresistance), weatherability, and price of the base material in selectingthe base material ingredient or ingredients.

[0035] A moment activator is blended in the base material tosignificantly increase the magnitude of dipole moment of the basematerial.

[0036] The moment activator itself may or may not provide a largemagnitude of dipole moment, however, in combination with the basematerial it can significantly promote the overall magnitude of dipolemoment in the base material.

[0037] The magnitude of dipole moment in the base material 11 will beincreased by three to ten times under the same temperature and energyconditions as exemplary shown in FIG. 3 by blending a moment activatortherein. The consumption of energy provided by the recovery of thedipoles in the base material is unexpectedly great, providing anunexpectedly improved total energy absorption/damping capability.

[0038] The moment activator which can provide such an unexpected effectmay be a compound or compounds having a benzothiazyl radical such asN,N-dicyclohexylbenzothiazyl-2-sulfonamide (DCHBSA),2-mercaptobenzothiazole (MBT), dibenzothiazylsulfide (MBTS),N-cyclohexylbenzothiazyl-2-sulfenamide (CBS),N-tert-butylbenzpthiazyl-2-sulfenamide (BBS),N-oxydiethylenebenzothiazyl-2-sulfonamide (OBS), orN,N-diisopropylbenzothiazyl-2-sulfenamide (DPBS), or a benzotriazylradical such as2-2′-hydroxy-3′-(3″,4″,5″,6″tetrahydrophthalimidemethyl)-5′-methylphenyl)-benzotriazole(2HPMMB), 2-2′-hydroxy-5′methylphenyl)-benzotriazole (2HMPB),2-2′-hydroxy-3′-t -butyl-5′-methylphenyl)-5chlorobenzotriazole(2HBMPCB), 2-2′-hydroxy-3′,5′-di-t-butylphenyl)-5-chlorobenzotriazole(2HDBPCB) having as a nucleus benzotriazole comprising an azole radicalbound to a benzene ring, to which a phenyl radical is bound, or adiphenylacrylate such as ethyl-2-cyano-3,3-di-phenylacrylate (ECDPA).

[0039] Moment activators have their own dipole moment. The magnitude ofdipole moment in a base material containing a moment activator issubject to the working temperature as well as the type and magnitude ofenergy applied to the base material. Accordingly, a moment activator tobe blended in a base material should be selected so as to provide thelargest possible magnitude of dipole moment in the base material,considering the working temperature and the type and magnitude of energyto be applied. When a polymer material is used as the base material fora vibration damping or sound absorptive material, it is important toselect a moment activator to be blended in the base material consideringthe compatibility of both, or their respective SP values, which shouldadvantageously be close for a better miscibility.

[0040] An energy conversion product according to this invention can beprovided by blending a selected base material and selected momentactivator and optionally additives such as a filler or dye, and moldingor spinning the mixture into a film, fibrous or block material.Conventional blending and molding or spinning means can be utilized.

BRIEF DESCRIPTION OF THE DRAWINGS

[0041]FIG. 1 is a schematic drawing showing a state of dipoles in a basematerial.

[0042]FIG. 2 is a schematic drawing showing a state of the dipoles inthe base material after subjection to energy.

[0043]FIG. 3 is a schematic drawing showing a state of dipoles in a basematerial where a moment activator is blended.

[0044]FIG. 4 is a graph showing a relationship between the dielectricconstant (∈′) and dielectric loss factor (∈″) in a base material.

[0045]FIG. 5 is a graph showing respective relationships between thetemperature and elastic tangents (tan δ) of Embodiment 1 and Comparison1.

[0046]FIG. 6 is a graph showing respective relationships between thetemperature and elastic tangents (tan δ) of Embodiments 2 to 5 andComparison 2.

[0047]FIG. 7 is a graph showing respective relationships between thetemperature and elastic tangents (tan δ) of Embodiments 6 to 9 andComparison 3.

[0048]FIG. 8 is a graph showing respective relationships between thetemperature and elastic tangents (tan δ) of Embodiments 10 to 12 andComparison 4.

[0049]FIG. 9 is a graph showing respective relationships between thetemperature and elastic tangents (tan δ) of Comparisons 5 to 9.

[0050]FIG. 10 is a graph showing respective relationships between thetemperature and loss factors (η) of Embodiments 13 and 14 and Comparison10.

[0051]FIG. 11 is a graph showing respective relationships between thetemperature and loss factors (η) of Samples 1 to 6.

[0052]FIG. 12 is a graph showing respective relationships between thetemperature and loss factors (η) of Samples 7 to 10.

[0053]FIG. 13 is a graph showing respective relationships between thetemperature and loss factors (η) of Samples 11 to 13.

[0054]FIG. 14 is a graph showing respective relationships between thetemperature and loss factors (η) of Samples 14 to 17.

[0055]FIG. 15 is a schematic drawing showing a sound absorptive filmcomprising a sound absorptive material according to this invention.

[0056]FIG. 16 is a schematic drawing showing a sound absorptive sheetcomprising sound absorptive fibers according to this invention.

[0057]FIG. 17 is a schematic drawing showing a sound absorptive foam ofthe present invention.

[0058]FIG. 18 is a schematic drawing showing a sound absorberincorporating a sound absorptive sheet according to the presentinvention.

[0059]FIG. 19 is a schematic drawing showing a porous polyurethane foamcontaining sound absorption fibers according to this invention.

[0060]FIG. 20 is a schematic drawing showing a sound damping paperincorporating sound absorptive fibers according to this invention.

[0061]FIG. 21 is a schematic drawing showing a sound damping fabricincorporating sound absorptive fibers according to this invention.

[0062]FIG. 22 is a graph showing the sound absorption performance ofSample 4 in relation to the frequency.

[0063]FIG. 23 is a graph showing the sound absorption performance ofSample 3 in relation to the frequency.

[0064]FIG. 24 is a graph showing the sound absorption performance ofSample 2 in relation to the frequency.

[0065]FIG. 25 is a graph showing the sound absorption performance ofSample 1 in relation to the frequency.

[0066]FIG. 26 is a graph showing respective relationships between thetemperature and dynamic loss tangents (tan δ) of the sound absorptivesheets according to Embodiments 15 to 17 and Comparisons 11 to 13.

[0067]FIG. 27 is a graph showing respective sound absorptionperformances of the sound absorptive sheets according to Embodiment 15and Comparison 11 in relation to the frequency.

[0068]FIG. 28 is a graph showing respective sound absorptionperformances of the sound absorptive sheets according to Embodiment 16and Comparison 12 in relation to the frequency.

[0069]FIG. 29 is a graph showing respective sound absorptionperformances of the sound absorptive sheets according to Embodiment 17and Comparison 13 in relation to the frequency.

[0070]FIG. 30 is a graph showing respective sound absorptionperformances of the test pieces of Embodiments 18 to 20 and Comparison14 in relation to the frequency.

[0071]FIG. 31 is a graph showing respective sound absorptionperformances of the test pieces of Embodiment 21 and Comparison 15 inrelation to the frequency.

[0072]FIG. 32 is a schematic drawing showing a shoe incorporating animpact absorptive material according to the present invention.

[0073]FIG. 33 is a schematic drawing showing an impact absorptiveplaster cast incorporating a non-woven cloth comprising impactabsorptive fibers of the present invention.

[0074]FIG. 34 is a schematic drawing showing a top cover of a bicyclesaddle comprising an impact absorptive material of the presentinvention.

[0075]FIG. 35 is a schematic drawing showing an impact absorptivebicycle handle grip comprising an impact absorptive material of thepresent invention.

[0076]FIG. 36 is a graph showing respective relationships between thethickness and impact resilience of the samples of Embodiment 22 andComparisons 16 to 20.

[0077]FIG. 37 is a front view showing an impact resilience measuringapparatus.

[0078]FIG. 38 is a side view showing the impact resilience measuringapparatus.

[0079]FIG. 39 is an enlarged view showing a portion of the impactresilience measuring apparatus.

[0080]FIG. 40 is a side view showing the enlarged portion of the impactresilience measuring apparatus.

[0081]FIG. 41 is a graph showing respective relationships between thethickness and impact resilience of the samples of Embodiments 22 to 25and Comparison 21.

[0082]FIG. 42 is an enlarged perspective view showing an impact absorberaccording to the present invention.

[0083]FIG. 43 is a schematic drawing showing an apparatus for measuringthe vibration acceleration level of the impact absorbers according toEmbodiment 26 and Comparisons 22 to 24.

[0084]FIG. 44 is a graph showing respective vibration accelerationlevels of the impact absorbers according to Embodiment 26 andComparisons 22 to 24.

[0085]FIG. 45 is a side view schematically showing an apparatus formeasuring the vibration acceleration level (dB) of the grip tapesaccording to Embodiment 27, Comparison 25 and Conventions 1 to 5.

[0086]FIG. 46 is a plan view of the apparatus of FIG. 45.

[0087]FIG. 47 is a graph showing the respective vibration accelerationlevels (dB) of the grip tapes according to Embodiment 27, Comparison 25and Conventions 1 to 5.

[0088]FIG. 48 is a schematic drawing showing an apparatus for measuringthe vibration acceleration level of the impact absorbers according toEmbodiments 28 to 31 and Comparisons 26 to 33.

[0089]FIG. 49 is a graph showing the respective vibration accelerationlevels of the impact absorbers according to Embodiments 28 to 31 andComparisons 26 to 33 as measured by the apparatus shown in FIG. 48.

[0090]FIG. 50 is a schematic drawing showing an apparatus for measuringthe vibration acceleration level of the impact absorbers as applied on asafety shoe (JIS product) according to Embodiments 28 to 31 andComparisons 26 to 33.

[0091]FIG. 51 is a graph showing the respective vibration accelerationlevels of the impact levels of the impact absorbers according toEmbodiments 28 to 31 and Comparisons 26 to 31 as measured by theapparatus shown in FIG. 50.

[0092]FIG. 52 is a graph showing respective relationships between thefrequency and electromagnetic absorptive capabilities of the test piecesaccording to Embodiments 32 to 35 and Comparison 34.

[0093]FIG. 53 is a graph showing respective relationships between thefrequency and electromagnetic wave absorption capabilities of theelectromagnetic wave absorptive layers according to Embodiments 36 to 39and Comparison 35.

[0094]FIG. 54 is a schematic drawing showing an apparatus for measuringthe piezoelectric property of the piezoelectric materials according toEmbodiments 40 to 42 and Comparison 36.

[0095]FIG. 55 is a schematic drawing showing endothermic pellets of thepresent invention.

[0096]FIG. 56 is a schematic drawing showing a casing of a seismicvibration-proof apparatus and a viscous fluid in the casing.

[0097]FIG. 57 is a graph showing a relationship between the loss factorand vibration energy absorption rate of conventional unconstrained andconstrained vibration dampers.

[0098]FIG. 58 is an enlarged front view of an impact absorber partiallycorrugated and laminated.

[0099]FIG. 59 is an enlarged front view of another impact absorbercomprising impact absorptive cylinders shown in FIG. 61 and sheetscovering both top and bottom surfaces thereof.

[0100]FIG. 60 is a cross sectional view of an impact absorptive foam ofthe present invention.

[0101]FIG. 61 is a perspective view of impact absorptive cylinders ofthe present invention.

[0102]FIG. 62 is a perspective view of a honeycomb impact absorber.

[0103]FIG. 63 is a schematic drawing showing front forks incorporatingan impact absorptive material according to this invention.

[0104]FIG. 64 is a schematic drawing showing another type of front forksincorporating an impact absorptive material according to this invention.

[0105]FIG. 65 is an enlarged cross sectional view showing another stateof the front forks of FIG. 64.

[0106]FIG. 66 is an enlarged cross sectional view showing a grip tapeaccording to the present invention.

[0107]FIG. 67 is an enlarged cross sectional view showing another griptape according to this invention.

[0108]FIG. 68 is a perspective view showing yet another grip tapeaccording to this invention.

[0109]FIG. 69 is a schematic drawing showing a shoe incorporating animpact absorptive shoe sole according to this invention.

BEST MODE FOR CARRYING OUT THE INVENTION

[0110] Energy conversion compositions according to the present inventionare now described in detail. First, a vibration damping material of thisinvention is described. The vibration damping material according to thisinvention includes a moment activator in its base material in an amountof 10 to 100 parts by weight in 100 parts by weight of the basematerial.

[0111] The base material is not limited to but may be a polymer materialsuch as polyvinyl chloride, polyethylene, polypropylene, ethylene-vinylacetate copolymer, polymethyl methacrylate, polyvinylidene fluoride,polyisoprene, polystyrene, styrene-butadiene-acrylonitrile copolymer,styrene-acrylonitrile copolymer, acrylonitrile-butadiene rubber (NBR),styrene-butadiene rubber (SBR), butadiene rubber (BR), natural rubber(NR), isoprene rubber (IR), or their selected blend. Polyvinyl chlorideis preferred for its workability and low cost.

[0112] The relationship between the magnitude of dipole moment and thevibration energy absorption property is described. FIG. 1 shows anatural state or original orientation of dipoles 12 in a base material11 prior to the transfer of a vibration energy thereto. In this state,the dipoles 12 are stable. However, when a vibration energy istransferred to the base material, the dipoles 12 in the base material 11are displaced into an unstable state such as shown in FIG. 2. Thedipoles 12 in the base material 11 are prompted to return to a stablestate such as shown in FIG. 1.

[0113] There is involved an energy consumption there. The vibrationenergy is assumed to be absorbed or damped through the consumption ofenergy provided by that displacement and recovery of the dipoles in thebase material 11.

[0114] Based on this vibration energy consumption, the dampingcapability of the base material 11 can be improved by increasing themagnitude of dipole moment in the base material 11. Accordingly, a basematerial inherently capable of providing large dipole moment in themolecules should be selected so as to provide a high vibration energyabsorption capability.

[0115] A base material inherently capable of providing a large magnitudeof dipole moment may be a polarity polymer such as polyvinyl chloride,chlorinated polyethylene, acrylic rubber (ACR), acrylonitrile-butadienerubber (NBR), styrene-butadiene rubber (SBR), or chloroprene rubber(CR). Such polarity polymers can also inherently provide considerablemechanical strength and workability.

[0116] As such a vibration damping material can be used on automobiles,interior materials, construction materials, and electric appliances, itis important to maximize the vibration energy damping capability atoperating temperatures (operating temperature region of −20° C. to −40°C.).

[0117] To maximize the vibration energy absorption capability in theoperating temperature region, this invention proposes use of a polymersuch as polyvinyl chloride, polyethylene, polypropylene, ethylene-vinylacetate copolymer, polymethyl methacrylate, polyvinylidene fluoride,polyisoprene, polystyrene, styrene-butadiene-acrylonitrile copolymer, orstyrene-acrylonitrile copolymer, to which a plasticizer such asdi-2-ethylhexalphthalate (DOP), dibutylphthalate (DBP), ordiisononylphthalate (DINP) is added to shift their glass transitionpoint or temperature (Tg) into the operating temperature region, or apolymer having a glass transition point within the operating temperatureregion itself such as acrylic rubber (ACR), acrylonitrile-butadienerubber (NBR), styrene-butadiene rubber (SBR), butadiene rubber (BR),natural rubber (NR), isoprene rubber (IR), chloroprene rubber (CR), orchlorinated polyethylene.

[0118] In selecting an appropriate polymer for the base material of avibration absorber or damper of the present invention, usability,moldability, availability, temperature property such as heat and coldresistance, weatherability, and price should also be taken intoconsideration.

[0119] The base material includes a moment activator in an amount of 10to 100 parts by weight in 100 parts by weight of the base material,which can promote dipole moment in the base material. The momentactivator may be a compound having a benzothiazyl or benzotriazylradical or a diphenylacrylate radical such asethyl-2-cyano-3,3-di-phenylacrylate.

[0120] To improve the vibration energy absorption capability, micascales, glass pieces, carbon fibers, calcium carbonate, barite, orprecipitated barium sulfate may be optionally blended in the basematerial.

[0121] A vibration absorber of the present invention can be provided bymixing such a base material and a moment activator, with an optionaladdition of such a filler, by a conventional melting and mixingapparatus such as a heat roll, Banbury mixer, two-axis kneader, orextruder.

[0122] Such a vibration damping material containing a moment activatorcan significantly promote dipole moment in the base material and providean excellently improved vibration energy absorption capability. Dipolemoment in the vibration damping material may be defined as thedifference in dielectric constant (∈′) between A and B shown in FIG. 4.Therefore, dipole moment increases as the difference in dielectricconstant (∈′) between A and B increases.

[0123]FIG. 4 is a graph showing a relationship between the dielectricconstant (c′) and dielectric loss factor (∈″). The relationship betweenthe dielectric constant (∈′) and dielectric loss factor (∈″) is given asfollows: Dielectric Loss Factor (∈″)=Dielectric Constant (∈′)×DielectricLoss Tangent (tan δ).

[0124] Through a lengthy research on vibration damping materials, theinventors have discovered that the vibration energy absorptioncapability can be improved by increasing the dielectric loss factor(∈″). The dielectric loss tangent (tan δ) indicating an electronicproperty of polymers is directly related to the elastic tangent (tan δ)indicating dynamic elasticity.

[0125] Through tests on the dielectric loss factor (∈″) of the vibrationdamping materials, the inventors have also found that when thedielectric loss factor is 50 or over at the frequency of 110 Hz, thedamping materials have a high elastic tangent (tan δ) and provide anexcellent vibration energy absorption capability.

[0126] Thanks to such an excellent vibration absorption capability, thevibration damping materials of the present invention can beadvantageously utilized as an unconstrained vibration damper.

[0127] Vibration dampers are categorized in two types, constrained andunconstrained. An unconstrained type of vibration dampers absorb or dampvibration energy through vibrations of a viscoelastic layer(macromolecular layer) provided by the vibration deformation of a platemember such as a steel plate and/or through frictional energyconsumption.

[0128] Conventional unconstrained vibration dampers do not provide aloss factor (η) 0.1 or greater as shown in FIG. 57. To provide such aloss factor, a conventional damper will necessarily become very thick orneed be constrained by sandwiching the damper material with a substrateand a constraining layer.

[0129] A thick unconstrained vibration damper may provide an improvedvibration energy absorption capability, however, it is technically hardto process such a thick material such as by cutting or bending it to adesired size and shape. In addition, such a thick vibration dampercannot easily be fixed on an application site.

[0130] Conversion of such a conventional vibration damping material intoa constrained type vibration damper requires a considerable cost, whichwill be rather heavy in weight anyway.

[0131] A vibration damping material of the present invention canappropriately solve such technical shortcomings of conventionalvibration damping materials. The unconstrained vibration damper of thepresent invention is capable of providing vibration energy absorptionwhich is comparable with that provided by conventional constrainedvibration dampers, and is much lighter and thinner than thoseconventional dampers.

[0132] The unconstrained vibration damper of the present inventioncontains in its base material a moment activator which can promotedipole moment in an amount of 101 to 500 parts by weight in 100 parts byweight of the base material.

[0133] The relationship between the dipole moment and vibration energyabsorption capability is described. FIG. 1 shows an original state ofdipoles 12 in a base material 11 prior to the transfer of a vibrationenergy thereon. In this arrangement, the dipoles 12 are stable.

[0134] When a vibration energy is transferred to the base material 11,the dipoles 12 in the base material 11 are displaced as shown in FIG. 2and held unstable. The dipoles 12 are then prompted to return to astable state such as shown in FIG. 1.

[0135] The vibration energy is assumed to be absorbed or damped throughthat process of energy consumption by the dipoles 12 in the basematerial 11.

[0136] Based on this assumption of vibration damping, the vibrationdamping capability of the base material 11 can be improved by increasingthe magnitude of dipole moment in the base material 11. Accordingly, apolymer inherently given a large dipole moment in the molecules can beadvantageously used to provide high vibration energy absorption.

[0137] Polymers whose molecules can inherently provide a large dipolemoment are polarity polymers such as polyvinyl chloride, chlorinatedpolyethylene, acrylic rubber (ACR), acrylonitrile-butadiene rubber(NBR), styrene-butadiene rubber (SBR), and chloroprene rubber (CR). Sucha polarity polymer provides an excellent mechanical strength and is easyto process.

[0138] As the unconstrained vibration damper of the present inventionmay be advantageously utilized on automobiles, interior materials,construction materials, or electric appliances, it is essential tomaximize the vibration energy damping capability in their operatingtemperature range

[0139] To maximize the vibration energy absorption capability within theoperating temperature range, a polymer which has or will have a glasstransition point in the operating temperature range shouldadvantageously be used as a base material. Such polymers are polyvinylchloride, polyethylene, polypropylene, ethylene-vinyl acetate copolymer,polymethyl methacrylate, polyvinylidene fluoride, polyisoprene,polystyrene, styrene-butadiene-acrylonitrile copolymer, andstyrene-acrylonitrile copolymer, to which a plasticizer such asdi-2-ethylhexalphthalate (DOP), dibutylphthalate (DBP), ordiisononylphthalate (DINP) is added to shift their glass transitionpoint or temperature (Tg) into the operating temperature range of −20°C. to 40° C., or polymers such as acrylic rubber (ACR),acrylonitrile-butadiene rubber (NBR), styrene-butadiene rubber (SBR),butadiene rubber (BR), natural rubber (NR), isoprene rubber (IR),chloroprene rubber (CR), and chlorinated polyethylene which themselvesinherently have a glass transition point (Tg) in the operatingtemperature range.

[0140] In selecting an appropriate polymer for the base material of avibration damper of the present invention, not only the magnitude ofdipole moment and the operating temperature range but also usability,moldability, availability, temperature property, weatherability, andprice are to be taken into consideration.

[0141] The base material is provided with a moment activator of acompound or compounds selected from among compounds containing abenzothiazyl or benzothiazyl radical, or a diphenylacrylate radical,such as ethyl-2-cyano-3,3-di-phenylacrylate.

[0142] 101 to 500 parts by weight of a moment activator is blended in100 parts by weight of a base material. If less than 101 parts by weightof a moment activator is mixed, the moment activator will not provide asufficient dipole moment promotion, whereas if more than 500 parts byweight of a moment activator is blended, insufficient miscibility withthe base material will result.

[0143] To select an appropriate moment activator to be blended into abase material, the miscibility (SP value) between the moment activatorand the base material should be taken into due consideration. The SPvalue of the moment activator and that of the base material should beclose enough to each other for desirable blending.

[0144] The magnitude of dipole moment in the base material is subject tothe base material component or components and the moment activator. Themagnitude is also subject to the working temperature and the magnitudeof energy transferred to the base material. Accordingly, the basematerial and the moment activator to be blended into the base materialshould be selected so as to provide the largest possible dipole momentfor a probable operation temperature range and magnitude of vibrationenergy to be applied.

[0145] A moment activator comprising a plurality of different compoundsor different moment activators may be blended in a base material, inwhich case two or more types of moment activators having substantiallydifferent glass transition points may advantageously be used to expandthe effective working temperature zone by combining their respectiveworking temperature ranges. Such moment activators may be selected fromamong the combinations of DCHP and DCHBSA or DCHP, DCHBSA and ECDPA fora base material of polyvinyl chloride.

[0146] In addition to such a moment activator, a filler or fillers suchas mica scales, glass pieces, carbon fibers, calcium carbonate, barite,or precipitated barium sulfate may be blended in the base material tofurther improve the vibration absorption capability of the basematerial. Preferably, 20 to 80 parts by weight of a filler or fillersare blended in the base material. When less than 20 parts by weight ofsuch a filler is blended, the filler will not sufficiently improve thevibration absorption capability, whereas if more than 80 parts by weightof such a filler is blended, the filler will not blend well in the basematerial or will reduce the mechanical strength of the vibration dampingproduct.

[0147] The unconstrained vibration damper of the present invention canbe obtained by mixing a base material and a moment activator andoptionally a filler by a conventional melt/mix apparatus such as a heatroll, Banbury mixer, two-axis kneader, or extruder.

[0148] As described above, the moment activator blended in the basematerial of the unconstrained vibration damper of the present inventioncan significantly promote dipole moment in the base material and providean excellent vibration energy absorption effect. The magnitude of dipolemoment in the unconstrained vibration damper is given as the differencein dielectric constant (∈′) between A and B shown in FIG. 4. Dipolemoment increases as the difference in dielectric constant (∈′) between Aand B shown in FIG. 4 increases.

[0149]FIG. 4 is a graph showing a relationship between the dielectricconstant (∈′) and the dielectric loss factor (∈″). The relationshipbetween the dielectric constant (∈′) and the dielectric loss factor (∈″)is given as follows: Dielectric Loss Factor (∈″)=Dielectric Constant(∈′)×Dielectric Loss Tangent (tan δ).

[0150] Through a lengthy research on unconstrained types of vibrationdampers, the inventors have found that the loss factor (η) increases asthe dielectric loss factor (∈″) increases. The dielectric loss factor(∈″) indicating an electronic property of polymers is correlated withthe loss factor (η) indicating a dynamic characteristic.

[0151] Testing on the dielectric loss factor (∈″) of the unconstrainedvibration dampers, the inventors have found that when the dielectricloss factor is 50 or larger at 110 Hz, the unconstrained vibrationdamping material has an excellent loss factor (h) and provides excellentvibration energy absorption.

[0152] The vibration damping materials described above can also beutilized as vibration damping or absorptive paints.

[0153] Conventionally vibration damping sheets are applied onautomobiles, interior materials, construction materials, and electricappliances where vibrations are inherent.

[0154] Such a vibration damping sheet is first cut to a size and shapecorresponding to an application site, which is often manually mounted onthe application site using an adhesive. The application of such avibration damper on a curbed portion or narrow gap is time consuming andproblematical.

[0155] In view of such disadvantages, conventional vibration dampingpaints have recently been proposed, in which mica scales are mixed inthe paint base material usually of a viscoelastic polymer such asrubber, plastic or asphalt. Such conventional vibration damping paintsprovide a damping layer by spraying or brushing means without requiringproblematical cutting or sticking on even curbed surfaces or in narrowgaps. As spray application is possible, a robot can be introduced toperform the application operation, substantially improving workefficiency and lowering cost.

[0156] Despite these advantages, as the thickness of the conventionalvibration damping films or layers provided with such a damping paint arelimited to 2 mm or so, the films cannot not provide sufficient andsubstantial vibration damping.

[0157] The vibration damping paint prepared according to the presentinvention can solve such a technical weakness and provide a thin butexcellent vibration damping layer or film.

[0158] The vibration damping paint according to this invention includesa moment activator in the base material, which can promote dipole momentin the paint.

[0159] The relationship between the dipole moment and vibration energyabsorption capability is explained. FIG. 1 shows an arrangement ofdipoles 12 in a vibration damping layer (base material) 11 prior to thetransfer of a vibration energy thereon. Here, the dipoles 12 are heldstable. However, when a vibration energy is transferred to the dampinglayer 11, the dipoles 12 in the layer 11 are displaced into an unstablestate such as shown in FIG. 2. The dipoles 12 then are prompted to moveor return to a stable state such as shown in FIG. 1.

[0160] There occurs energy consumption in the process. The vibrationenergy is greatly absorbed through that energy consumption processprovided by the displacement and recovery of the dipoles 12 in thedamping film or base material 11.

[0161] The vibration damping capability of the damping layer 11 can beimproved by promoting dipole moment in the damping film 11. Accordingly,a material which can inherently provide large dipole moment in themolecules should be used for the base material of the vibration dampingpaint.

[0162] Such a material may be a polarity polymer such as polyvinylchloride, chlorinated polyethylene, acrylic rubber (ACR),acrylonitrile-butadiene rubber (NBR), styrene-butadiene rubber (SBR), orchloroprene rubber (CR).

[0163] Since the vibration damping paint according to this invention islikely applied on automobiles, interior materials, constructionmaterials, and electric appliances, it is essential that the vibrationenergy damping capability is maximized in the operation temperaturerange or −20 C. to 40 C.

[0164] To maximize the vibration energy absorption capability in theoperation temperature range, this invention proposes that a polymer orpolymers which will have a glass transition point in the operatingtemperature region be used as the base material, such as polyvinylchloride, polyethylene, polypropylene, ethylene-vinyl acetate copolymer,polymethyl methacrylate, polyvinylidene fluoride, polyisoprene,polystyrene, styrene-butadiene-acrylonitrile copolymer, and/orstyrene-acrylonitrile copolymer, to which a plasticizer such asdi-2-ethylhexalphthalate (DOP), dibutylphthalate (DBP), ordiisononylphthalate (DINP) is added to shift their glass transitionpoint (Tg) into the operating temperature range of −20 C. to 40 C., or apolymer or polymers which inherently have a glass transition pointthere, such as acrylic rubber (ACR), acrylonitrile-butadiene rubber(NBR), styrene-butadiene rubber (SBR), butadiene rubber (BR), naturalrubber (NR), isoprene rubber (IR), chloroprene rubber (CR), and/orchlorinated polyethylene.

[0165] Besides the above compounds, other materials such as polyurethaneor asphalt materials which are conventionally used as vibration dampingpaint base materials can be blended as well.

[0166] In selecting an appropriate base material for a vibration dampingpaint, not only the magnitude of dipole moment and the operatingtemperature region but also usability, easiness to process,availability, temperature property, weatherability, and price are to beduly considered.

[0167] The moment activator to be blended in the base material isadvantageously selected from compounds containing a benzothiazyl orbenzothiazyl radical or compounds containing a diphenylacrylate radicalsuch as ethyl-2-cyano-3,3-di-phenylacrylate.

[0168] Preferably, 10 to 100 parts by weight of a moment activator isblended in 100 parts by weight of a base material. If less than 10 partsby weight is mixed, the dipole moment will not be sufficiently promoted,whereas more than 100 parts by weight will lead to insufficientmiscibility with the base material and thus insufficient durability orintegrity.

[0169] To select an appropriate moment activator to be blended in thepaint, the miscibility between the moment activator and the paint basematerial should be excellent, or both SP values should be close enoughto each other.

[0170] The magnitude of dipole moment depends on the paint base materialand moment activator used. The magnitude of dipole moment also varieswith the operating temperature and is affected by the magnitude ofenergy transferred to the vibration damping paint layer. Accordingly,the paint base material and moment activator should be selectedappropriately to provide the largest possible dipole moment byconsidering the expected working temperature and magnitude of vibrationenergy.

[0171] A plurality of different moment activators or a moment activatorcomprising a plurality of activating compounds may be blended in a basematerial, in which case it is advantageous that they respectively havesufficiently different glass transition points so as to expand theworkable or effective temperature region. Such moment activators may beselected from the combinations of DCHP and DCHBSA or DCHP, DCHBSA andECDPA for a base material of polyvinyl chloride.

[0172] In addition, a filler or fillers such as mica scales, glasspieces, glass fibers, carbon fibers, calcium carbonate, barite, orprecipitated barium sulfate may be selectively and optionally blendedinto the base material to further improve the absorption capability andincrease the mechanical integrity of the vibration damping paint.

[0173] Preferably, 10 to 90 parts by weight of a filler is blended in100 parts by weight of the base material. Less than 10 parts by weightwill not sufficiently improve the absorption capability, whereas morethan 90 parts by weight will be impractical as the integrity of the basematerial will be weakened.

[0174] The vibration damping paint according to this invention may beprovided in an emulsion form by mixing the paint material and momentactivator and an optional filler and dispersing the mixture in water oralcohol. Other materials such as a dispersing agent, wetting agent,thickener, antifoaming agent, or colorant may be optionally added.

[0175] To use such vibration damping paints, a conventional air spraygun, airless spray gun, or brush may be used.

[0176] As described above, a moment activator is blended in a vibrationdamping paint base material to significantly promote dipole moment inthe paint and provide an excellently improved vibration energyabsorption capability. The magnitude of dipole moment in the dampingpaint is represented by the difference in dielectric constant (∈′)between A and B shown in FIG. 4. The magnitude of dipole momentincreases as the difference in dielectric constant (∈′) between A and Bincreases.

[0177]FIG. 4 shows a relationship between the dielectric constant (∈′)and the dielectric loss factor (∈″), which is given as follows:Dielectric Loss Factor (∈″)=Dielectric Constant (∈′)×Dielectric LossTangent (tan δ).

[0178] The inventors have discovered that both the loss factor (η) andthe loss tangent (tan δ) increase as the dielectric loss factor (∈″)increases. That is, the dielectric loss factor (∈″) indicating anelectronic property of polymers is correlated with the loss factor (η)and loss tangent (tan δ) indicating dynamic characteristics.

[0179] Tests on the dielectric loss factor (∈″) of those vibrationdamping paints have proved that when the dielectric loss factor is 50 orlarger at the frequency of 110 Hz, a vibration damping layer formed withthose damping paints provides an excellently improved loss factor (h)and loss tangent (tand), thus an excellent vibration energy absorptioncapability.

[0180] Next, sound or noise absorptive materials of the presentinvention are described.

[0181] Conventional sound absorptive or damping materials are preparedof rock fibers, glass wool, or open cell foam polyurethane moldings,often covered with a film material. In such a sound absorptive material,an acoustic energy hits and passes through the fibrous or poroussurface, and loses its energy as heat through friction therewith.Accordingly, how to increase surface acoustic resistance of the fibrousor porous surface was a main concern to improve the sound damping ofsuch conventional sound absorptive materials.

[0182] Such a conventional sound absorptive material need be relativelythick to provide sufficient sound absorption, particularly toeffectively damp sound of a low frequency such as 1,000 Hz or less, or500 Hz or less in particular. However, the thickness cannot be increasedwithout inviting various accompanying shortcomings.

[0183] Sound absorptive materials according to this invention canprovide, even when made very thin, excellent absorption of sound ornoise including sound of a low frequency such as 1,000 Hz or less, oreven 500 Hz or less.

[0184] The sound absorptive material of the present invention may bemade into a sound absorptive film, fiber (strands), foam, paper, andmolding. The sound absorptive material of the present invention includesa moment activator (or activators) which can promote dipole moment inits base material.

[0185] The base material may be a polymer material such as polyvinylchloride, polyethylene, polypropylene, ethylene-vinyl acetate copolymer,polymethyl methacrylate, polyvinylidene fluoride, polyisoprene,polystyrene, styrene-butadiene-acrylonitrile copolymer,styrene-acrylonitrile copolymer, polyester, polyurethane, polyamide,polyvinylidene, polyacrylonitrile, polyvinylalcohol, cellulose,acrylonitrile-butadiene rubber (NBR), styrene-butadiene rubber (SBR),butadiene rubber (BR), natural rubber (NR), isoprene rubber (IR), ortheir selected mixture.

[0186] Sound hits and passes through the fibrous or porous surface andis excellently damped through conversion into frictional heat.

[0187] The sound energy is further damped when the sound collidesagainst the base material. The dipoles 12 in the base material 11 asshown in FIG. 1 are displaced to a state such as shown in FIG. 2 byrotation or shifting of phase within the base material 11.

[0188] Prior to the application of a sound energy, the dipoles 12 in thebase material 11 are stable, however, the collision of the sound causesdisplacement of the dipoles 12 into an unstable state.

[0189] The dipoles 12 are then prompted to go back to a stable state.

[0190] Energy is then consumed. The sound absorption function isprovided through the generation of frictional heat on the surface of thebase material and the consumption of energy by the displacement andrecovery of the dipoles 12 within the base material 11.

[0191] Sound absorption provided by the present invention is assumed tobe associated with both the magnitude of surface resistance per unitarea of the base material (as in conventional sound absorptivematerials) and the magnitude of the dipole moment provided in the basematerial 11. The inventors' experiment has shown that the sound dampingcapability of the base material 11 is improved by increasing themagnitude of dipole moment in the base material 11.

[0192] The magnitude of dipole moment is subject to the base material,though, even if the same polymer material is used, the magnitude of thedipole moment to be provided in the base material varies with theoperation temperature and the frequency of sound. The magnitude ofdipole moment is also affected by the magnitude of sound energy appliedto the base material. Thus, the polymer for the base material should beselected so as to provide the largest possible magnitude of dipolemoment, considering the probable working temperature, frequency ofsound, and magnitude of sound energy for a particular application of thesound damping material of the present invention.

[0193] To choose an appropriate polymer for the base material, not onlythe magnitude of dipole moment in the base material but also usability,moldability, availability, temperature property, weatherability, andprice should be duly considered in accordance with a particularapplication.

[0194] The sound absorptive material according to this inventioncontains in the base material a moment activator which can significantlypromote dipole moment in the base material.

[0195] The moment activator is a compound or compounds containing abenzothiazyl or benzothiazyl radical or a diphenylacrylate radical suchas ethyl-2-cyano-3,3-di-phenylacrylate.

[0196] The sound absorptive material may be obtained by mixing anappropriately selected base material and such a moment activator with anoptional corrosion inhibitor or dye as desired, and molding or spinningthe mixture into films, fibers or blocks. A conventional molder orspinner may be used to provide the sound absorptive products of thepresent invention.

[0197] In the sound absorptive material containing a moment activator,the magnitude of dipole moment in the base material significantlyincreases and provides excellent damping of sound energy.

[0198] The magnitude of dipole moment is defined as the difference indielectric constant (∈′) between A and B shown in FIG. 4.

[0199] The magnitude of dipole moment increases as the difference indielectric constant (∈′) between A and B increases.

[0200]FIG. 4 shows a relationship between the dielectric constant (∈′)and the dielectric loss factor (∈″). The relationship between thedielectric constant (∈′) and the dielectric loss factor (∈″) is given asfollows: Dielectric Loss Factor (∈″)=Dielectric Constant (∈′)×DielectricLoss Tangent (tan δ).

[0201] A strenuous research on sound absorptive materials, the inventorshave found that the energy absorption capability can be greatly improvedby increasing the dielectric loss factor (∈″).

[0202] Through study on the dielectric loss factor (∈″) of soundabsorptive materials, the inventors have also discovered that excellentenergy absorption is provided when the dielectric loss factor is 7 orgreater at 110 Hz.

[0203] The sound absorption material according to the present inventioncan be used as a sound absorptive sheet which may be used as Japaneseslide door paper, wall paper or ceiling cloth.

[0204] Conventional sound absorptive sheets incorporate rock fibers,glass wool or felt. In such a conventional sound absorptive sheet, soundis damped through conversion into frictional heat.

[0205] The surface acoustic resistance of the component fibers of theconventional sound absorptive sheet can be improved somewhat, however,such a conventional sound absorptive sheet is required to have athickness of 5 or 10 mm, or even 20 to 30 mm to provide sufficient noisedamping. Thus, such a thick material has been utilized as a back-fillingmaterial for doors, walls or ceiling panels, not directly as door paper,wall paper or ceiling cloth.

[0206] The sound absorptive sheet according to this invention caneffectively solve the shortcomings and can be utilized directly as asheet of paper or cloth.

[0207] The sound absorptive sheet of the present invention may take aform of a fibrous sheet on which a polymer material is deposited.Although this sheet is thin like paper, it can provide sufficient soundabsorption.

[0208] Such a fibrous sheet may be any sheet composed of fibers of thepresent invention. A non-woven fabric may be advantageously utilized.

[0209] An appropriate polymer material or materials to be used as a basematerial of the present invention are blended with a moment activatorwhich can magnify the dipole moment in the base material.

[0210] The relationship between the magnitude of dipole moment and thesound absorption capability is described again hereunder. FIG. 1 showsan exemplary arrangement of dipoles 12 in a polymer material (basematerial) 11 prior to application of a sound energy.

[0211] The arrangement of the dipoles 12 is stable. A sound energydisplaces the dipoles 12 in the base material 11 into an unstable statesuch as shown in FIG. 2, which are prompted to return to a stable state.

[0212] Sound energy consumption takes place then. The sound absorptioncapability unique to the present invention seems provided by thisconsumption of energy provided through the displacement and recovery ofthe dipoles 12 in the polymer material or base material 11.

[0213] Based on this theory of sound absorption, the sound absorptioncapability of the polymer material 11 can be improved by increasing themagnitude of dipole moment in the polymer material 11. Accordingly, itis advantageous to use a polymer material inherently having a largedipole moment in the molecules so as to provide improved soundabsorption.

[0214] Polarity polymers can provide a large magnitude of dipole moment.Such polarity polymers may be polyvinyl chloride, chlorinatedpolyethylene, acrylic rubber (ACR), acrylonitrile-butadiene rubber(NBR), styrene-butadiene rubber (SBR), and chloroprene rubber (CR). Sucha polarity polymer can provide an excellent mechanical strength and iseasy to process.

[0215] The sound absorptive sheet according to this invention may beused as door paper, wall paper or ceiling cloth, so it is advantageousto maximize the sound absorption capability in the operating temperatureregion or −20 C. to 40 C.

[0216] To maximize the sound absorption capability in the operatingtemperature region, the sound absorptive sheet according to thisinvention selectively comprises a polymer or polymers which have a glasstransition point falling in the operating temperature region, such aspolyvinyl chloride, polyethylene, polypropylene, ethylene-vinyl acetatecopolymer, polymethyl methacrylate, polyvinylidene fluoride,polyisoprene, polystyrene, styrene-butadiene-acrylonitrile copolymer,and styrene-acrylonitrile copolymer, to which a plasticizer such asdi-2-ethylhexalphthalate (DOP), dibutylphthalate (DBP), ordiisononylphthalate (DINP) is added to shift the glass transition point(Tg) into the operating temperature region of −20 C. to 40 C., orpolymers such as acrylic rubber (ACR), acrylonitrile-butadiene rubber(NBR), styrene-butadiene rubber (SBR), butadiene rubber (BR), naturalrubber (NR), isoprene rubber (IR), chloroprene rubber (CR), andchlorinated polyethylene which themselves have a glass transition point(Tg) in the operating temperature region of −20 C. to 40 C.

[0217] In selecting an appropriate polymer material, not only themagnitude of dipole moment and the operating temperature region but alsousability, moldability, availability, temperature property,weatherability, and price are to be duly considered for a particularusage.

[0218] The moment activator to be blended may be a single compound or aplurality of compounds selected from ones containing a benzothiazyl orbenzothiazyl radical and ones containing a diphenylacrylate radical suchas ethyl-2-cyano-3,3-di-phenylacrylate.

[0219] Preferably, 10 to 300 parts by weight of a moment activator ismixed in 100 parts by weight of a base polymer material. If less than 10parts by weight is mixed, the addition of the moment activator will notprovide sufficient promotion of dipole moment, whereas if more than 300parts by weight of a moment activator is mixed, the moment activatorwill not sufficiently blend with the polymeric base material.

[0220] Accordingly, in selecting an appropriate moment activator to beblended, the miscibility between the moment activator and polymeric basematerial should appropriately be considered, or the SP values of bothshould be close enough to each other.

[0221] The magnitude of dipole moment is dependent on the polymermaterial and moment activator. The magnitude of dipole moment alsovaries with the operation temperature as well as affected by themagnitude of sound energy applied. Thus, the polymer base material andmoment activator should be selected so as to provide the largestpossible amount of dipole moment, taking the expected temperature andmagnitude of sound energy into due consideration.

[0222] The sound absorptive sheet according to this invention can beprovided in an emulsion form comprising a selected polymer materialblended with a selected moment activator, which is provided on a fibrousbase sheet. The amount of the polymer material deposited on the fibroussheet is not particularly limited to but is preferably 20 to 300 g/m2,more preferably 40 to 200 g/m2. Less than 20 g/m2 of the polymermaterial deposited on the sheet will not provide sufficient soundabsorption, whereas more than 300 g/m2 of the polymer material depositedon the sheet will give very poor appearance and degraded nature.

[0223] It is well known in the field of sound absorptive materials thatthe sound absorption capability of a sound absorptive material issubject to the frequency of sound. The sound absorptive sheet of thepresent invention can cope with various types of sounds by controllingits thickness or size. For example, for low frequencies, the thicknessof the sound absorptive sheet is reduced and/or its area is increased.For high frequencies, the thickness of the sheet is increased and/or itsarea is reduced.

[0224] As described above, in the sound absorptive sheet of the presentinvention comprising a fibrous sheet on which are deposited a selectedpolymer base material and moment activator blended therewith, themagnitude of dipole moment in the polymer base material is significantlypromoted and provides excellent sound absorption. The magnitude ofdipole moment in the sound absorptive sheet is defined as the differencein dielectric constant (∈′) between A and B shown in FIG. 4. That is,the magnitude of dipole moment increases as the difference in dielectricconstant (∈′) between A and B increases.

[0225]FIG. 4 is a graph showing a relationship between the dielectricconstant (∈′) and the dielectric loss factor (∈″). The relationshipbetween the dielectric constant (∈′) and the dielectric loss factor (∈″)is given as follows: Dielectric Loss Factor (∈″)=Dielectric Constant(∈′)×Dielectric Loss Tangent (tan δ).

[0226] Through research on sound absorptive sheets, the inventors havediscovered that the sound energy absorption capability can be improvedby increasing the dielectric loss factor (∈″).

[0227] Studying the dielectric loss factor (∈″) of the sound absorptivesheets of the present invention, the inventors have found that thesheets provide excellently improved sound absorption when the dielectricloss factor is 7 or greater at the frequency of 110 Hz.

[0228] The sound absorptive material according to this invention can beincorporated into a foamed sound absorptive sheet to be applied onautomobiles, interior materials, construction materials, or electricappliances.

[0229] Conventional foamed sound absorptive materials utilize foamedmoldings provided by a polymer such as polyurethane, polyethylene, orpolyvinyl chloride. When sound collides with such a conventional foamedsound absorptive material, vibrations are transmitted to the porousportions in the sound absorptive material, where the viscous friction ofair takes place, partially converting the sound energy into heat, andproviding damping of the sound energy.

[0230] A problem pertaining to such conventional foamed sound absorptivematerials is that they do not provide sufficient damping for sounds of afrequency below 2,000 Hz.

[0231] To sufficiently absorb and damp a sound of a frequency below2,000 Hz, a conventional foamed sound absorptive material needs to bethick, as thick as 3.4 cm for sound of 10 KHz and even 3.4 m for soundof 100 Hz, which has been impractical for application due to limitationof available space and cost.

[0232] Attempts have been made to promote the material density,expansion rate, or porosity rate of conventional foamed dampers toimprove their damping capability to damp sounds of frequencies below2,000 Hz. The improvement with such attempts have been only 20 to 30% atbest. Provision of sufficient sound absorption has not been successfulwith conventional noise dampers.

[0233] Foamed sound absorptive materials according to this invention canappropriately cope with these shortcomings and sufficiently absorb soundof frequencies below 2,000 Hz.

[0234] A foamed sound damper of the present invention may be provided byfoam molding. The foamed molding may be provided by foaming a polymersuch as polyurethane, polyvinylalcohol, polyvinyl chloride, chlorinatedpolyethylene, polyethylene, polypropylene, ethylene-vinyl acetatecopolymer, polymethyl methacrylate, polystyrene,styrene-butadinene-acrylonitrile copolymer, polyvinylformal, epoxy,phenol, urea, or silicon, or rubber polymer such as acryl rubber (ACR),acrylonitrile-butadinene rubber (NBR), styrene-butadinene rubber (SBR),butadiene rubber (BR), natural rubber (NR), isoprene rubber (IR), orchloroprene rubber (CR), by conventional bubbling means using a thermaldecomposing foaming agent or volatile solvent, or by generating aninactive gas to be absorbed by the polymer under a high pressure andprovide foaming under a normal pressure.

[0235] The expansion rate of such a foam may be arbitrarily controlledas desired for a particular application, while it is preferred toprovide 5 to 50 times of expansion, more preferably 10 to 30 times theoriginal polymer material. If this expansion rate is less than 5 times,the damping capability will be insufficient, whereas if this rate ismore than 50 times, the mechanical strength will be sacrificed. Thedamping capability increases as the number of cells and density of thefoamed molding increase. Thus, the expansion rate should be determinedtaking such factors into due consideration.

[0236] The foamed molding may have an open cell structure or closed cellstructure depending on its particular application or the type of sound(high or low frequency).

[0237] The foamed sound absorber of the present invention contains amoment activator in its base material which can promote the magnitude ofdipole moment in the product. The relationship between the magnitude ofdipole moment and the sound absorption capability is again explained.

[0238] It is known that when sound collides against the foamed soundabsorptive material, air vibrations are transmitted to the porousportions within the sound absorptive material, causing viscous frictionof air within the porous portions, which partially converts the soundenergy into heat energy, thereby providing partial sound damping.

[0239] The vibrations are attenuated by the resistance from airmovement. The inventors have found that there is involved anotherexcellent sound absorption that differs from the above sound absorptionmechanism.

[0240] The inventors have focused their attention on the dipoles in thefoamed molding which are subject to displacement and recovery when soundenergy is applied thereon.

[0241] Details of the finding are given below. FIG. 1 shows dipoles 12in a foamed molding (base material) 11 prior to the propagation of sound(sound energy). The dipoles 12 are stable there. When a sound energy isprovided, the dipoles 12 are displaced in the foamed molding 11 into anunstable state as shown in FIG. 2, which are prompted to return to theirstable state such as shown in FIG. 1.

[0242] Energy is greatly consumed during this process. The soundabsorption capability unique with the invention is assumed to beprovided through the consumption of energy through the displacement andrecovery of the dipoles 12.

[0243] The foam of the present invention can provide excellent soundabsorption through the consumption of sound energy provided by theviscous friction of air in the porous portions together with thedisplacement and recovery of the dipoles in the foamed material.

[0244] The sound absorption capability of the foamed molding 11 can bepromoted by promoting the dipole moment. Accordingly, it is essential touse a foam material inherently possessing large dipole moment in themolecules so as to provide a greatly improved sound absorptioncapability.

[0245] Such a material inherently possessing large dipole moment may bepolarity polymers such as polyvinyl chloride, chlorinated polyethylene,acrylic rubber (ACR), acrylonitrile-butadiene rubber (NBR),styrene-butadiene rubber (SBR), and chloroprene rubber (CR). Such apolarity polymer is excellent in mechanical strength and is easy toprocess.

[0246] The foamed sound absorptive material according to this inventionmay be applied on automobiles, interior materials, constructionmaterials, or electric appliances, so it is essential to maximize thesound absorption capability in the operating temperature range of −20 C.to 40 C.

[0247] To maximize the sound absorption capability in the operatingtemperature region, the foamed sound absorptive material according tothis invention comprises a polymer which has or will have a glasstransition point in the operating temperature region. A polymer whichwill have a glass transition point in the operating temperature regionmay be polyvinyl chloride, chlorinated polyethylene, polyethylene,polypropylene, ethylene-vinyl acetate copolymer, polymethylmethacrylate, polystyrene, or styrene-butadiene-acrylonitrile copolymer,to which a plasticizer such as di-2-ethylhexalphthalate (DOP),dibutylphthalate (DBP), or diisononylphthalate (DINP) is added to shifttheir glass transition point or temperature (Tg) into the operatingtemperature region of −20 C. to 40 C., or a rubber polymer such asacrylic rubber (ACR), acrylonitrile-butadiene rubber (NBR),styrene-butadiene rubber (SBR), butadiene rubber (BR), natural rubber(NR), isoprene rubber (IR), or chloroprene rubber (CR) which inherentlyhas a glass transition point (Tg) in the operating temperature region of−20 C. to 40 C.

[0248] An appropriate polymer material should be selected consideringnot only the magnitude of dipole moment and the operating temperatureregion but also usability, moldability, availability, temperatureproperty, weatherability, and price.

[0249] A moment activator to be blended with such a base polymermaterial may be selected from polymers containing a benzothiazyl orbenzothiazyl radical and ones containing a diphenylacrylate radical suchas ethyl-2-cyano-3,3-di-phenylacrylate.

[0250] Preferably, 10 to 200 parts by weight of a moment activator ismixed in 100 parts by weight of a foaming polymer.

[0251] If less than 10 parts by weight of a moment activator is mixed,the addition of the moment activator will not sufficiently promote thedipole moment, whereas if more than 200 parts by weight is blended,insufficient miscibility with the foaming polymer will result.

[0252] To select an appropriate moment activator to be blended with afoaming polymer, the miscibility between the moment activator and theforming polymer should be considered, that is the SP values of bothshould be close enough.

[0253] The magnitude of dipole moment to be provided in the polymericbase material depends on the types of the moment activator and formingpolymer.

[0254] The same materials will provide different magnitude of dipolemoment when the working temperature is different. The magnitude ofdipole moment is also affected by the magnitude of sound energy.Accordingly, the moment activator and foaming polymer should be selectedso as to provide the largest possible magnitude of dipole momentconsidering those factors.

[0255] It is known in the field of sound absorptive materials that thesound absorption capability of a material is subject to the type ofsound or frequency. Conventional foamed sound absorptive materials copewith different types of sound by increasing or reducing their thickness.For low frequencies, the thickness of the material is increased, whilefor high frequencies, the thickness of the material is reduced.

[0256] As described above, the moment activator is blended in a foamingpolymer material to significantly increase the magnitude of dipolemoment in the foamed molding to provide a greatly improved soundabsorption capability. The magnitude of dipole moment in the foamedsound absorptive material (foamed molding) is defined as the differencein dielectric constant (∈′) between A and B shown in FIG. 4. That is,the magnitude of dipole moment increases as the difference in dielectricconstant (∈′) between A and B increases.

[0257]FIG. 4 shows a relationship between the dielectric constant (∈′)and the dielectric loss factor (∈″). The relationship between thedielectric constant (∈′) and the dielectric loss factor (∈″) is given bythe following equation: Dielectric Loss Factor (∈″)=Dielectric Constant(∈′)×Dielectric Loss Tangent (tand).

[0258] Through a lengthy research on foamed sound absorptive materials,the inventors have found that the sound energy absorption capability canbe improved by increasing the dielectric loss factor (∈″).

[0259] Through study on the dielectric loss factor (∈″) of the foamedsound absorptive materials, the inventors have found that the materialsprovide excellently improved sound absorption when the dielectric lossfactor is 10 or larger at the frequency of 110 Hz.

[0260] Although the foamed sound absorptive material according to thisinvention can provide excellent sound absorption alone, they may befixedly deposited on a synthetic resin film of polyvinyl chloride,polyethylene, polypropylene, or polyethylene or a fibrous sheet ofpaper, cloth, or non-woven fabric, which provide combined sound dampingof the synthetic resin film or fibrous sheet and the foamed soundabsorptive material of the invention, further improving the soundabsorption capability of the product.

[0261] The sound absorptive material according to this invention can beutilized as sound absorptive fiber or sound absorptive yarn or fibrousmaterial containing such fibers.

[0262] Conventional sound absorptive fibers or fibrous materialscomprise rock wool, glass wool or felt. Such a conventional soundabsorptive material damps sound energy through conversion intofrictional heat provided on the fiber surface and through the fibers.

[0263] As conventional sound absorptive materials provide sound dampingthrough such a process, sufficient sound absorption cannot be expectedwithout increasing the thickness of the damper or fiber diameter, fiberlength and/or fiber density. Therefore, a conventional sound dampertends to become thick and large to provide an effective performance,which cannot practically be used as door paper, wall paper, casings orcovers for electric appliances.

[0264] Sound absorptive fibers, yarns and fibrous bodies according tothis invention can adequately solve the above problem.

[0265] The fibers of the present invention themselves have an improvedsound absorption capability.

[0266] The sound absorptive fibers of the present invention arecharacterized in that a moment activator is blended in the base polymermaterial, which can significantly promote dipole moment in the basepolymer material. The polymer material of the fibers may be selectedfrom polyolefine such as polyethylene, chlorinated polyethylene,polypropylene, polyester, and polyurethane, polyamide such as nylon 6,nylon 66, or nylon 12, polyvinyl chloride, polyvinylidene chloride,polyacrylonitrile, polyvinylalcohol, cellulose, and their derivatives.

[0267] Such a polymer is blended with a moment activator which canincrease the magnitude of dipole moment in the polymer. The relationshipbetween the magnitude of dipole moment and the sound absorptioncapability is again explained. The mechanism of sound absorption by thesound absorptive fibers is that when a sound collides and passes thoughthe fibrous surface, sound energy is partially consumed as frictionalheat and damped. The inventors have found that there is involved anothersignificant sound absorption mechanism that differs from the above knownsound absorption mechanism. The dipoles in the base polymer aredisplaced into an unstable state and then return to a stable state,consuming substantial energy.

[0268] Further details are given below. FIG. 1 shows an arrangement ofdipoles 12 in a base polymer (base material) 11 prior to the propagationof a sound or sound energy. The arrangement of the dipoles 12 is stablethere. When a sound propagates onto the base polymer, the dipoles 12 inthe polymer are displaced into an unstable state, which are prompted toreturn to a stable state.

[0269] Substantial energy is then consumed. The sound absorption of thepresent invention is assumed to be additionally provided through thatconsumption of energy provided by the displacement and recovery of thedipoles 12 in the base polymer 11.

[0270] Accordingly, the sound absorption capability of the basepolymer11 can be improved by increasing the magnitude of dipole momentin the polymer 11. Thus, a polymer inherently has a large magnitude ofdipole moment in the molecules can provide an improved sound absorptioncapability. A polymer which can inherently provide a large magnitude ofdipole moment may be a polarity polymer such as polyvinyl chloride,chlorinated polyethylene, polyurethane, polyamide, polyvinylidenechloride, polyacrylonitrile, or cellulose.

[0271] Sound absorptive fibers according to this invention can be usedin varied ways, so it is essential to maximize the sound absorptioncapability in the operating temperature range or −20 C. to 40 C.

[0272] To maximize the sound absorption capability within the operatingtemperature region, the sound absorptive fibers according to thisinvention comprise a polymer which has or will have a glass transitionpoint in the operating temperature region. Polymers which will have aglass transition point in the operating temperature region may bepolyvinyl chloride, polyethylene, or polypropylene, to which aplasticizer such as di-2-ethylhexalphthalate (DOP), dibutylphthalate(DBP), or diisononylphthalate (DINP) is blended to shift their glasstransition point or temperature (Tg) into the operating temperatureregion of −20 C. to 40 C., or polymers such as chlorinated polyethyleneor polyurethane which inherently have a glass transition point (Tg) inthe operating temperature region of −20 C. to 40 C.

[0273] In selecting an appropriate polymer, not only the magnitude ofdipole moment in the molecules of the base material and the operatingtemperature region but also usability, moldability, availability,temperature property, weatherability, and price should be appropriatelyconsidered.

[0274] A moment activator to be blended with such a polymer may be apolymer containing a benzothiazyl or benzothiazyl radical, or adiphenylacrylate radical such as ethyl-2-cyano-3,3-di-phenylacrylate.Preferably, 10 to 200 parts by weight of a moment activator is mixed in100 parts by weight of a base polymer. If less than 10 parts by weightis mixed, poor improvement will result, whereas if more than 200 partsby weight is mixed, the miscibility will be poor and the product willprovide poor integrity.

[0275] To select an appropriate moment activator, the miscibilitybetween the moment activator and the base polymer should besatisfactory, that is, the SP values of both should be close enough.

[0276] The magnitude of dipole moment is subject to the types of thebase polymer and moment activator. The magnitude of dipole moment varieswith the temperature at the time a sound energy is transferred to thebase polymer. The magnitude of dipole moment is also affected by themagnitude of the sound energy. Thus, the base polymer and momentactivator should be selected so as to provide the largest possiblemagnitude of dipole moment taking into consideration the expectedtemperature and magnitude of sound energy.

[0277] It is known that the sound absorptive capability of a materialdepends on the type of sound, that is, its frequency. The soundabsorptive fibers of the present invention can cope with practically anytype of sound with an appropriately selected base polymer or polymersfor fibers and moment activator to be blended in the base material.

[0278] As described above, the moment activator in the mixturesignificantly promotes the dipole moment of the base material of thesound damping fibers of the present invention and provides excellentlyimproved sound absorption. The magnitude of dipole moment in the basematerial is defined as the difference in dielectric constant (∈′)between A and B shown in FIG. 4. The magnitude of dipole momentincreases as the difference in dielectric constant (∈′) between A and Bincreases.

[0279]FIG. 4 is a graph showing a relationship between the dielectricconstant (∈′) and the dielectric loss factor (∈″), which is given asfollows: Dielectric Loss Factor (∈″)=Dielectric Constant (∈′)×DielectricLoss Tangent (tan δ).

[0280] A research on sound absorptive fibers conducted by the inventorshas revealed that the sound energy absorption capability can be improvedby increasing the dielectric loss factor (∈″). Studying the dielectricloss factor (∈″) of the sound absorptive fibers based on this findinghas also revealed that the base polymer material provides an excellentsound absorption capability when the dielectric loss factor is 10 orlarger at the frequency of 110 Hz.

[0281] It is desirable that effective sound absorption is provided overa wide frequency range. The sound absorptive fibers according to thisinvention satisfy this demand by incorporating a moment activator and apolymer which respectively exhibit substantially different soundabsorption characteristics in different frequency ranges.

[0282] Such expansion of frequency effect can be provided as well byblending with a base material a plurality of different moment activatorsor compounds exhibiting substantially different frequencycharacteristics, or by blending a plurality of moment activatorcompounds in a plurality of different base polymers having substantiallydifferent frequency characteristics, or by blending a moment activatorin such a plurality of polymers.

[0283] The sound absorptive fibers according to this invention can beprovided from a base material comprising an appropriately selectedpolymer or polymers and moment activator by any appropriate conventionalspinning method. The sound absorptive fibers can also be obtained in acomposite form of a core-sheath, side-by-side, sea-island, or sandwichtype using appropriate conventional spinning means.

[0284] The sound absorptive fibers according to this invention can beutilized for household articles such as door paper, wall paper, ceilingcloth, curtains, mats, or carpets, vehicle base materials such as carflooring or wall materials, casings or covers for refrigerators orwashing machines, wall or floor materials for buildings, film materialsfor domes, or construction materials for roads or rail bases.

[0285] The sound absorptive fibers of the present invention may take aform comprising a selected polymer blended with a moment activator,which provides fiber surface. The various factors of such soundabsorptive fibers such as fiber type, material or shape can bedetermined as desired.

[0286] The cover or surface of such sound absorptive fibers may whollyor partially comprise a polymer containing a moment activator.

[0287] Such a wholly covered type of sound absorptive fibers may be asheath-core type or sea-island type composite fibers, whose sheath orsea portions are composed of a polymer including a moment activator.

[0288] Such wholly covered type sound absorptive fibers can also beprovided by coating conventional fiber surface with a polymer materialcontaining a moment activator.

[0289] Such a partially covered type of sound absorptive fibers may be aside-by-side type, sea-island type, or sandwich composite type ofcomposite fibers, whose one side, island or layer portions are composedof a polymer including a moment activator.

[0290] Such partially covered sound absorptive fibers can also beprovided by partially coating conventional fiber surface with a polymercontaining a moment activator.

[0291] A polymer to be coated on the fiber surface may be ethylene-vinylacetate copolymer, polymethacryl acid methyl, polyvinylidene fluoride,polyisoprene, polystyrene, styrene-butadinene-acrylonitrile copolymer,or styrene-acrylonitrile copolymer, or a rubber polymer such as acrylrubber (ACR), acrylonitrile-butadinene rubber (NBR), styrene-butadinenerubber (SBR), butadiene rubber (BR), natural rubber (NR), isoprenerubber (IR), or chloroprene rubber (CR).

[0292] The polymer is applied onto the fibrous surface in an emulsionform or dispersion in water or alcohol. Optionally, a dispersant orthickener is further blended in the polymer. The blend is dispersed andmixed using a conventional mixer or disperser such as a dissolver,Banbury mixer, planetary mixer, grain mill, open kneader, or vacuumkneader. The mixture is then deposited on the fibrous surface with aconventional applicator such as an air spray gun, airless spray gun, orbrush.

[0293] A plurality of different moment activator compounds whichrespectively exhibit substantially different sound absorptioncharacteristics in substantially different frequency ranges may beblended in a base polymer to provide in combination effective soundabsorption over a wide frequency range. Equally, a plurality of suchmoment activator compounds may be blended with a plurality of differentbase polymers having substantially different frequency characteristics,or a single moment activator compound may be blended with a plurality ofsuch different base polymers to provide an expanded frequency propertyfor damping noise or sound.

[0294] The sound absorptive fibers of the present invention can providesound absorptive yarn or fibrous bodies. The sound absorptive yarn maybe formed of a plurality of different sound absorptive fibers,advantageously, having substantially different sound absorptioncharacteristics in substantially different frequency ranges.

[0295] The sound absorptive yarn may be provided either in a filament orspun yarn configuration. The length, thickness, number or twists offilaments or staples for the filament yarn or spun yarn may bedetermined as desired.

[0296] A plurality of different sound absorptive fibers of differentsound absorption characteristics over different frequency ranges(500-1,000 Hz, 1,000-2,000 Hz, and/or 2,000-3,000 Hz) may be bundledtogether and twisted into a single sound absorptive yarn or fibrousbody, which can provide a combined wider scope of effective dampingproperty relative to the frequency, that is, such a sound absorptiveyarn may be particularly useful in the frequency range between 500 and3,000 Hz.

[0297] Such a sound absorptive yarn can incorporate, besides soundabsorptive fibers, certain functional fibers such as high-strength,flame-retardant or antibacterial fibers to provide multiple fiberfunctions.

[0298] The sound absorptive fibrous body is provided nearly identicallywith the sound absorptive yarn except that the fibrous body may be madeinto other configurations.

[0299] The sound absorptive fibrous body may be made into a sheet suchas cloth, non-woven cloth, or paper, or other forms such as a block,plate, ball honeycomb, or pleat. To provide a non-woven cloth or paper,the sound absorptive fibers are directly processed, while to providecloth, the sound absorptive fibers are first formed into soundabsorptive yarn, which is then woven or knitted. The fibrous body mayalso be composed of a combination of the sound absorptive fibers andyarn.

[0300] A plurality of different sound absorptive fibers which exhibitsubstantially different sound absorption characteristics oversubstantially different frequency ranges may be bundled together andtwisted into a single yarn or fibrous body so as to provide a wideeffect over a wider range of frequency, such as by combining soundabsorptive fibers exhibiting effective sound absorption in the frequencyrange between 500 and 1,000 Hz and another exhibiting effective soundabsorption in the frequency range between 1,000 and 2,000 Hz to provideyarn exhibiting widened effective sound absorption over the frequencyrange between 500 to 2,000 Hz and provide a fabric with the soundabsorption effect over the frequency range between 500 to 2,000 Hz, orby weaving yarn of sound absorptive fibers exhibiting effective soundabsorption in the frequency range between 500 to 1,000 Hz as weft andyarn of sound absorptive fibers exhibiting effective sound absorption inthe frequency range between 1,000 to 2,000 Hz as warp to provide afabric having widened effective sound absorption over the range of 500to 2,000 Hz, or by knitting yarn of sound absorptive fibers exhibitingeffective sound absorption in the frequency range between 500 and 1,000Hz, yarn of sound absorptive fibers exhibiting effective soundabsorption in the frequency range between 1,000 and 2,000 Hz, and yarnof sound absorptive fibers exhibiting effective sound absorption in thefrequency range between 2,000 and 3,000 Hz to together provide a knitexhibiting a widened effective sound absorption over the frequency rangebetween 500 to 3,000 Hz.

[0301] As regards non-woven cloth, a plurality of different soundabsorptive fibers exhibiting substantially different sound absorptioncharacteristics over substantially different frequency ranges may becombined to provide a fibrous web which provides a widened effect over awidened frequency range by combining sound absorptive fibers exhibitinga sound absorption effect in the frequency range between 500 and 1,000Hz and sound absorptive fibers exhibiting a sound absorption effect inthe frequency range between 1,000 and 2,000 Hz to provide a non-wovenfabric exhibiting effective sound absorption over the frequency rangebetween 500 to 2,000 Hz, or combining sound absorptive fibers exhibitinga sound absorption effect in the frequency range between 500 and 1,000Hz, sound absorptive fibers exhibiting a sound absorption effect in thefrequency range between 1,000 and 2,000 Hz, and sound absorptive fibersexhibiting a sound absorption effect in the frequency range between2,000 and 3,000 Hz to obtain non-woven cloth exhibiting widenedeffective sound absorption over the frequency range between 500 to 3,000Hz.

[0302] Sound absorptive paper can be provided similarly as with thesound absorptive non-woven fabric described above.

[0303] Besides incorporating such different sound absorption fibers, thesound absorptive fibrous body may contain functional fibers such ashigh-strength, flame-retardant, antibacterial and/or deodorant fibers toprovide multiple fiber functions.

[0304] The sound absorptive fibrous body may be made into a compositeconfiguration by fixing the sound absorptive fibrous body on a fibroussheet, or a synthetic resin film, corrugated fiber board, wooden board,or metallic plate.

[0305] Next, an impact absorptive material according to this inventionis described.

[0306] Conventionally, foamed impact absorptive materials comprising athermoplastic resin such as polystyrene, polyethylene, polypropylene, orpolyurethane are utilized on walls or fences, helmet lining, interiorarticles for vehicles or airplanes, or car bumpers.

[0307] For packaging fragile products such as glass articles fortransportation, a synthetic resin foam of polystyrene or polyurethane,or a protection board where synthetic resin sheets (cardboard) andcorrugated synthetic resin sheets (cardboard) are laminated as shown inFIG. 58 have been utilized to prevent damage to the articles duringtransportation.

[0308] A synthetic resin molded into a synthetic resin foam or honeycombstructure shown in FIG. 59 has been used alone or in a composite form inconstruction materials such as wall or floor materials or certainfacilities or rock sheds which are subject to impacts P such as blastsor underwater impacts.

[0309] In applications on vehicle air bags or shoe soles, a liquid suchas water, a gas such as air, or gel sealed in a flexible casing hasconventionally been in use to absorb impacts applied to the casing.

[0310] Conventional impact absorptive materials have the followingdisadvantages.

[0311] When an impact is applied on a cushion having a honeycomb orcorrugated structure or an impact absorber comprising a synthetic resinfoam such as a polyurethane foam, the device gradually deforms orcollapses. The device does not return to its original state when theimpact is removed, which leads to degradation of its damping capability.

[0312] Since such a conventional impact absorber only gradually deformsand collapses to provide impact damping, it does not instantly providesufficient impact absorption. Consequently, the fragile products to beprotected may not be adequately protected.

[0313] Besides, an impact cushion of a honeycomb or corrugated structureis costly to manufacture. A conventional impact absorptive syntheticresin foam, despite its relative easiness to manufacture and process, isfragile and likely damaged and degraded with heat, sun rays or asolvent.

[0314] A conventional impact absorber which uses air, water or gel has arecovery function and may provide impact absorption each time it issubjected to an impact. Such a conventional impact absorber comprising acasing containing air, water or gel requires a relatively large over alldimension to provide effective impact absorption, limiting itsapplications.

[0315] The impact absorptive materials or absorbers according to thisinvention can solve these technical weaknesses and have improved impactabsorption capabilities. The impact absorptive materials of the presentinvention, even when made thin, can provide sufficient mechanicalstrength and excellent impact absorption from the moment of impact, aswell as an instant recovery function thereafter.

[0316] The impact absorptive material according to this invention can beused, for example, as walls or fences in athletic fields, helmetlinings, interior materials for vehicles and airplanes, car bumpers,saddles, grips, packing cushioning materials, construction materialssuch as floor materials, certain facilities or rock sheds which aresubject to impact loads P such as blasts or underwater impacts, sportsgoods such as training shoes, protections, gloves or head gears, medicalarticles such as plaster casts, mats, or supporters, gun bottoms,shoulder pads, or bulletproof jackets.

[0317] The impact absorptive material of the invention is characterizedin that the base material contains a moment activator which can increasethe magnitude of dipole moment therein.

[0318] The resin component for the base material should provideeffective sound absorption at working temperatures. Such a resin may bea polymer such as polyvinyl chloride, polyethylene, chlorinatedpolyethylene, polypropylene, ethylene-vinyl acetate copolymer,polymethyl methacrylate, polyvinylidene fluoride, polyisoprene,polystyrene, styrene-butadiene-acrylonitrile copolymer,styrene-acrylonitrile copolymer, acrylonitrile-butadiene rubber (NBR),styrene-butadiene rubber (SBR), butadiene rubber (BR), natural rubber(NR), isoprene rubber (IR), or their selected mixture. Polyvinylchloride is preferred for its moldability and low cost.

[0319] When such a base material composed of a selected polymer orpolymers is subjected to an impact, dipoles 12 present in the basematerial 11 are displaced. The displacement of the dipoles 12 may be bytheir rotation or phase shifting within the base material 11.

[0320] Prior to the application of an impact energy, the dipoles 12 inthe base material 11 are stable. When an impact energy is applied on thebase material 11, the dipoles 12 in the base material 11 are displacedinto an unstable state, which are then prompted to return to a stablestate.

[0321] Energy is then efficiently consumed. The impact absorption uniqueto the present invention is assumed to be provided through thatconsumption of energy.

[0322] The impact absorption is assumed to be associated with the dipolemoment in the base material 11. Therefore, the impact absorbingcapability of the base material 11 can be improved by increasing themagnitude of dipole moment in the base material 11.

[0323] The magnitude of dipole moment is subject to the type of basematerial or resin material. The same polymer material provides adifferent magnitude of dipole moment when the working temperaturevaries.

[0324] effective sound absorption at working temperatures. Such a resinmay be a polymer such as polyvinyl chloride, polyethylene, chlorinatedpolyethylene, polypropylene, ethylene-vinyl acetate copolymer,polymethyl methacrylate, polyvinylidene fluoride, polyisoprene,polystyrene, styrene-butadiene-acrylonitrile copolymer,styrene-acrylonitrile copolymer, acrylonitrile-butadiene rubber (NBR),styrene-butadiene rubber (SBR), butadiene rubber (BR), natural rubber(NR), isoprene rubber (IR), or their selected mixture. Polyvinylchloride is preferred for its moldability and low cost.

[0325] When such a base material composed of a selected polymer orpolymers is subjected to an impact, dipoles 12 present in the basematerial 11 are displaced. The displacement of the dipoles 12 may be bytheir rotation or phase shifting within the base material 11.

[0326] Prior to the application of an impact energy, the dipoles 12 inthe base material 11 are stable. When an impact energy is applied on thebase material 11, the dipoles 12 in the base material 11 are displacedinto an unstable state, which are then prompted to return to a stablestate.

[0327] Energy is then efficiently consumed. The impact absorption uniqueto the present invention is assumed to be provided through thatconsumption of energy.

[0328] The impact absorption is assumed to be associated with the dipolemoment in the base material 11. Therefore, the impact absorbingcapability of the base material 11 can be improved by increasing theamount of dipole moment in the base material 11.

[0329] The magnitude of dipole moment is also affected by the magnitudeof impact energy. Thus, the resin material should be selected so as toprovide the largest possible magnitude of dipole moment considering theexpected working temperature and magnitude of impact energy.

[0330] In selecting an appropriate polymer for the base material, notonly the magnitude of dipole moment in the base material but alsousability, moldability, availability, temperature capability,weatherability, and price should be duly considered for particularusage.

[0331] The resin component is blended with a moment activator which cansignificantly increase the magnitude of dipole moment therein.

[0332] The moment activator may comprise a plurality of compoundsselected from compounds containing a benzothiazyl or benzothiazylradical or ones containing a diphenylacrylate radical.

[0333] The magnitude of dipole moment is subject to the moment activatoras well.

[0334] Even if the same moment activator is used, the magnitude of thedipole moment varies with the operation temperature. The magnitude ofdipole moment is also affected by the magnitude of impact energy appliedto the base material.

[0335] Thus, the moment activator should be selected so as to providethe largest possible magnitude of dipole moment considering the possibleoperation temperature and magnitude of impact energy.

[0336] To select a moment activator appropriately, the miscibilitybetween the moment activator and the resin base material should be takeninto due consideration, that is, the SP values of both should be closeenough.

[0337] The impact absorptive material of the present invention may beprovided by mixing the resin base material and moment activator, and

[0338] The magnitude of dipole moment is subject to the type of basematerial or resin material. The same polymer material provides adifferent magnitude of dipole moment when the working temperaturevaries. optionally a dye, corrosion inhibitor, electric control agent,stabilizer, or wetting agent as desired by conventional melting/mixingmeans such as a heat roll, Banbury mixer, two-axis kneader, or extruder.

[0339] As described above, such a moment activator is mixed in the basepolymer of the impact absorptive material to significantly promotedipole moment in the base material. The magnitude of dipole moment inthe impact absorptive material is given as the difference in dielectricconstant (∈′) between A and B shown in FIG. 4.

[0340] The magnitude of dipole moment increases as the difference indielectric constant (∈′) between A and B increases.

[0341]FIG. 4 is a graph showing a relationship between the dielectricconstant (∈′) and the dielectric loss factor (∈″). The relationshipbetween the dielectric constant (∈′) and the dielectric loss factor (∈″)is given as follows: Dielectric Loss Factor (∈″)=Dielectric Constant(∈′)×Dielectric Loss Tangent (tan δ).

[0342] Through a lengthy research on impact absorptive materials, theinventors have found that the impact absorption capability can beimproved by increasing the dielectric loss factor (∈″). In other words,the dielectric loss tangent (tan δ) indicating an electric property ofpolymers is substantially correlated with the impact resilience (%)indicating a dynamic characteristic.

[0343] Upon study of the dielectric loss factor (∈″) of the impactabsorptive materials based on this finding, the inventors have alsofound that the materials have a high impact resilience (%) and provideexcellent shock absorption when the dielectric loss factor is 50 orlarger at the frequency of 110 Hz.

[0344] The configuration of the impact absorber is not limited to asheet and can be provided in varied forms depending on applicationconditions. The configuration shown in FIG. 60 may be obtained by mixinga moment activator in a resin base and adding a foaming agent to providethe foamed molding.

[0345] The damper shown in FIG. 61 may be provided by molding a polymermatrix blended with a moment activator into cylinders to be arranged andcoupled together. The damper shown in FIG. 62 may be obtained by moldingthe resin into a honeycomb configuration while the damper shown in FIG.58 may be obtained using corrugate processing in which sheet-likemoldings and corrugated moldings are laminated.

[0346] The damper shown in FIG. 59 may be provided by sandwiching impactabsorptive cylinders such as shown in FIG. 60 with impact absorptivesheets.

[0347] The impact absorber according to this invention is alsoapplicable onto front forks installed between an automobile body andshaft to absorb and reduce impact such as vibrations from a roadsurface.

[0348] A conventional front fork has spring means between a shaft-sideouter tube and a body-side inner tube so that the spring force can actas a cushion to absorb and reduce impact from the road surface, and/orseal oil between the shaft-side outer tube and the body-side inner tubeto provide air cushioning for absorbing and damping impact.

[0349] The front fork with the built-in spring means, however, issubject to stress fatigue from repeated use, which will not retain itsoriginal capability over a long period of use. On the other hand, thefront fork with the air-cushion damper requires a large amount of oil toprovide sufficient air compression force, which substantially increasecost and overall weight. In addition, such a conventional front forkmechanism requires a large number of parts such as oil sealing chambers,air chambers, cylinders, or shafts, which further pushes up cost.

[0350] A front fork with both spring means and damper means mounted on acar body and shaft will provide improved shock damping, however, bothmeans must be well balanced. This balancing is a very complicatedoperation requiring professional skills.

[0351] A front fork which utilizes an elastic body such as rubber orfoamed urethane instead of spring or damper means is also conventionallyused in many applications, chiefly on bicycles, thanks to its simplestructure and light weight.

[0352] However, due to the low impact absorption capability of such aconventional elastic body, the front fork cannot sufficiently absorb andreduce impact or shock.

[0353] The front fork according to this invention can appropriately copewith such problems and provide an unexpectedly excellent impactabsorption.

[0354] A front fork 11 in FIG. 63 of the present invention comprises ashaft-side outer tube 12 and a body-side inner tube 13 movably insertedin the outer tube 12, wherein an impact absorber 14 including a momentactivator is disposed between the outer and inner tubes 12 and 13 asshown.

[0355] The base material of the impact absorber may be polyvinylchloride, polyethylene, chlorinated polyethylene, polypropylene,ethylene-vinyl acetate copolymer, polymethyl methacrylate,polyvinylidene fluoride, polyisoprene, polystyrene,styrene-butadiene-acrylonitrile copolymer, styrene-acrylonitrilecopolymer, acrylonitrile-butadiene rubber (NBR), styrene-butadienerubber (SBR), butadiene rubber (BR), natural rubber (NR), isoprenerubber (IR), or their selected mixture. Polyvinyl chloride is preferredfor its moldability and low cost.

[0356] In the impact absorber provided with such a polymer as the basematerial and a moment activator, the relationship between the magnitudeof dipole moment and the impact absorption capability is given asfollows.

[0357] The general mechanism of impact absorption in the impact absorberis such that an impact applied to the impact absorber is partiallyconverted into heat energy, providing some impact damping. Throughresearch on the mechanism of impact absorption, the inventors have foundthat the displacement and recovery of the dipoles in the impact absorberbase material provides significant energy damping.

[0358] The details are given below. FIG. 1 shows dipoles 12 in theimpact absorptive base material 11 prior to application of an impact.The arrangement of the dipoles 12 is stable. When an impact is applied,the dipoles 12 in the impact absorptive base material 11 get displacedto an unstable state such as shown in FIG. 2, which are prompted toreturn to a stable state such as shown in FIG. 1.

[0359] Energy is then absorbed or damped. The impact absorptioncapability is assumed to be provided through the absorption orconversion of energy by the displacement and recovery of the dipoles 12in the impact absorptive base material 11.

[0360] Based on this mechanism of impact absorption, the impactabsorption capability of the impact absorptive material 11 can beimproved by increasing the magnitude of dipole moment in the impactabsorptive material 11.

[0361] Thus, it is essential to use a base material inherently having alarge magnitude of dipole moment in the molecules in order to provideexcellently improved impact absorption.

[0362] Materials inherently having a large magnitude of dipole momentmay be polarity polymers such as polyvinyl chloride, chlorinatedpolyethylene, acrylic rubber (ACR), acrylonitrile-butadiene rubber(NBR), styrene-butadiene rubber (SBR), and chloroprene rubber (CR).

[0363] The front fork according to this invention can significantlyabsorb and reduce impact from the road surface and can excellentlyfunction in a wide range of temperature or between about −20 C. andabout 40 C. It is advantageous to use as the base material a polymerwhich has or will have a glass transition point in this operatingtemperature zone because the impact absorption capability is maximizednear the glass transition point of the polymer.

[0364] A polymer to have a glass transmission point in that operatingtemperature region may be polyvinyl chloride, polyethylene,polypropylene, ethylene-vinyl acetate copolymer, polymethylmethacrylate, polystyrene, or styrene-butadiene-acrylonitrile copolymer,to which a plasticizer such as di-2-ethylhexylphthalate (DOP),dibutylphthalate (DBP), or diisononylphthalate (DINP) is added to shiftthe glass transition point (Tg) into the operating temperature region,or a polymer such as acrylic rubber (ACR), acrylonitrile-butadienerubber (NBR), styrene-butadiene rubber (SBR), butadiene rubber (BR),natural rubber (NR), isoprene rubber (IR), chloroprene rubber (CR), orchlorinated polyethylene which inherently has a glass transition point(Tg) in the operating temperature region.

[0365] In selecting an appropriate base material, not only the magnitudeof dipole moment in the molecules and the operating temperature regionbut also usability, moldability, availability, temperature capability,weatherability, and price should be duly considered.

[0366] A plurality of moment activators or moment activator compoundsmay be blended, which may be selected from compounds containing abenzothiazyl or benzothiazyl radical or a diphenylacrylate radical suchas ethyl-2-cyano-3,3-di-phenylacrylate.

[0367] Preferably, 10 to 200 parts by weight of a moment activator ismixed in 100 parts by weight of a base material. If less than 10 partsby weight of a moment activator is blended, the dipole moment will notbe sufficiently improved, whereas if more than 200 parts by weight of amoment activator is mixed, the moment activator will not be sufficientlyblended with the base material or may provide an insufficient mechanicalstrength.

[0368] To select an appropriate moment activator to be blended in thebase material, not only the magnitude of dipole moment but also themiscibility between the moment activator and the base material should beconsidered, that is, the SP values of both should be close enough.

[0369] The magnitude of dipole moment is subject to the base materialand moment activator. Even if the same base material and momentactivator are used, the magnitude of dipole moment varies with theworking temperature. The magnitude of dipole moment is also affected bythe magnitude of energy transferred to the base material. Thus, the basematerial and moment activator should be selected so as to provide thelargest possible magnitude of dipole moment considering the possibleworking temperature and magnitude of sound energy.

[0370] A filler such as mica scales, glass pieces, glass fibers, carbonfibers, calcium carbonate, barite, or precipitated barium sulfate may beadditionally blended in the base material to further improve theabsorption capability. Preferably, 10 to 80% by weight of a filler isblended in the base material.

[0371] If less than 10% by weight is mixed, the filler will notsufficiently improve the absorption capability, whereas if more than 80%by weight is mixed, it will not be blended appropriately or reduce themechanical strength of the product.

[0372] The impact absorptive material of the present invention for afront fork can be manufactured by mixing a base material and momentactivator, and as an option a filler, dispersant, or thickener asdesired using a conventional melt/mix apparatus such as a dissolver,Banbury mixer, planetary mixer, grain mill, open kneader, or vacuumkneader.

[0373] As described above, the moment activator is blended in the basematerial to significantly increase the magnitude of dipole moment in thebase material in order to provide an excellently improved impactabsorption capability. The magnitude of dipole moment in the impactabsorptive material is defined as the difference in dielectric constant(∈′) between A and B shown in FIG. 4. That is, the magnitude of dipolemoment increases as the difference in dielectric constant (∈′) between Aand B increases.

[0374]FIG. 4 is a graph showing a relationship between the dielectricconstant (∈′) and the dielectric loss factor (∈″). The relationshipbetween the dielectric constant (∈′) and the dielectric loss factor (∈″)is given as follows: Dielectric Loss Factor (∈″)=Dielectric Constant(∈′)×Dielectric Loss Tangent (tan δ).

[0375] Through a lengthy research on impact absorptive materials forfront forks, the inventors have found that the energy absorptioncapability or impact absorption capability can be improved by increasingthe dielectric loss factor (∈″). Through study on the dielectric lossfactor (∈″) of the above impact absorptive material based on thisfinding, the inventors have also found that the material providesexcellent shock absorption when the dielectric loss factor is 50 orlarger at the frequency of 110 Hz.

[0376] The above impact absorptive material is provided between theouter tube and the inner tube of a front fork as shown in FIG. 63 toabsorb and reduce impact from the road surface.

[0377] In FIG. 63, reference numeral 15 designates a bracket for fixingthe front forks 11 to a car body. The inner tube 13 is inserted into theouter tube 12. The impact absorptive material 14 disposed between thebottom of the outer tube 12 and the lower end of the inner tube 13absorbs and damps impact or shock from the road surface.

[0378]FIGS. 64 and 65 show another type of front forks 11 which can dampimpact in both ways, upward and downward. The front fork 11 shown inFIG. 64 has the outer tube 12 on the shaft side 16 and the inner tune 13fixed to the body via the bracket 15. The inner tube 13 can be insertedinto the outer tube 12. A T-shaped support lever 17 is provided in thecenter of the bottom of the outer tube 12, and a coil spring 19 isprovided between the upper end surface of the supporting lever 17 and acap 20 attached to the upper end of the inner tube 13 to urge the innertube 13 against the outer tube 12 in the upward direction.

[0379] The lower end of the inner tube 13 extends from the upper end ofthe support lever 17 to the lower part, with a stopper 21 providedinside the lower end of the inner tube 13. A ring-like impact absorptivematerial 14 is provided between the stopper 21 and the upper end of thesupport lever 17.

[0380] In the front fork 11, the spring 19 damps impact on the innertube 13 inserted in the outer tube 12 in the upward direction, while theimpact absorptive material 14 damps impact in the downward direction.

[0381] The dimension of the impact absorptive material can beappropriately decided.

[0382] The impact absorptive material according to this invention can beused as grip tapes as described below.

[0383] In recent years, impact absorptive tapes are conventionally usedon sports equipment such as tennis or badminton rackets, baseball bats,or golf clubs, or handles of bicycles or motorbikes, or tools such ashammers.

[0384] Such sports equipment, or handles or hand tools with suchconventional shock damping tapes on can provide limited impactabsorption and therefore their users receive uncomfortable feelings fromuse. Their elbows may eventually be damaged.

[0385] Accordingly, professionals and artisans as well as general publicdemand a grip tape which can provide much improved shock damping.

[0386] Commercially available conventional grip tapes generally comprisea foam resin material such as polyvinyl chloride or polyurethane foam.

[0387] Due to the low impact absorption capability of such a foam resinmaterial, conventional grip tapes do not provide sufficient damping ofimpact.

[0388] The grip tape according to this invention can effectively solvethis shortcoming and can provide unexpectedly excellent impactabsorption.

[0389] The grip tape 11 shown in FIG. 66 consists of a single layer ofonly a tape substrate 12, and the grip tape 11 shown in FIG. 67 has anadhesive layer 13 under the tape substrate 12. The grip tape 11 shown inFIG. 68 has a large number of through holes 14 in the tape substrate 12for ventilation to evacuate moisture from the users.

[0390] The configuration of the grip tape according to this inventioncan be varied according to application or use conditions. For example,recesses and protrusions can be provided on the tape surface to improvegrip, or a shock absorptive adhesive layer may be provided under thesubstrate.

[0391] The tape substrate of the grip tape according to this inventionis described. The substrate base material may be a polymer such aspolyvinyl chloride, polyethylene, chlorinated polyethylene,polypropylene, ethylene-vinyl acetate copolymer, polymethylmethacrylate, polyvinylidene fluoride, polyisoprene, polystyrene,styrene-butadiene-acrylonitrile copolymer, styrene-acrylonitrilecopolymer, acrylonitrile-butadiene rubber (NBR), styrene-butadienerubber (SBR), butadiene rubber (BR), natural rubber (NR), isoprenerubber (IR), or their appropriate mixture. Polyvinyl chloride ispreferred for its moldability and low cost.

[0392] In the tape substrate of such a polymer, the relationship betweenthe magnitude of dipole moment and the impact absorption capability isas follows.

[0393] Impact vibration transferred to the grip tape is partiallyconverted into heat.

[0394] This energy conversion damps the impact vibration on the griptape. Through research on the mechanism of impact absorption, theinventor have found that the displacement and recovery of the dipoles inthe tape substrate provides excellent energy damping.

[0395] The details are given below. FIG. 1 shows an arrangement ofdipoles 12 in a tape substrate (base material) 11 prior to thepropagation of an impact. The dipoles 2 are stable there. When an impactor shock is applied on the substrate, the dipoles 12 are displaced intoan unstable state such as shown in FIG. 2, which are prompted to returnto a stable state such as shown in FIG. 1.

[0396] Energy is then absorbed or consumed excellently. The impactabsorption is assumed to be provided through the absorption of energyprovided by the displacement and recovery of the dipoles in the tapesubstrate (base material) 11.

[0397] Based on this assumption, the impact absorption capability of thetape substrate 11 can be improved by increasing the magnitude of dipolemoment in the tape substrate 11. Thus, the substrate material shouldhave large dipole moment in the molecules to provide an excellent impactabsorption capability.

[0398] Materials which inherently have large dipole moment may bepolarity polymers such as polyvinyl chloride, chlorinated polyethylene,acrylic rubber (ACR), acrylonitrile-butadiene rubber (NBR),styrene-butadiene rubber (SBR), and chloroprene rubber (CR).

[0399] The tape is usually used within a temperature range between about−20 C. and about 40 C. It is essential that a polymer which has or willhave a glass transition point in this operating temperature region beused to maximize the damping effect, as the glass transition point of apolymer provides the most effective damping according to the inventors'experiments.

[0400] Polymers which will have a glass transmission point in such anoperating temperature region may be polyvinyl chloride, polyethylene,polypropylene, ethylene-vinyl acetate copolymer, polymethylmethacrylate, polystyrene, or styrene-butadiene-acrylonitrile copolymer,to which a plasticizer such as di-2-ethylhexalphthalate (DOP),dibutylphthalate (DBP), or diisononylphthalate (DINP) is added to shifttheir glass transition point (Tg) into the operating temperature region,or polymers such as acrylic rubber (ACR), acrylonitrile-butadiene rubber(NBR), styrene-butadiene rubber (SBR), butadiene rubber (BR), naturalrubber (NR), isoprene rubber (IR), chloroprene rubber (CR), andchlorinated polyethylene, which themselves have a glass transition point(Tg) in the operating temperature region.

[0401] In selecting an appropriate tape substrate material, not only themagnitude of dipole moment in the base polymer and the operatingtemperature region but also usability, moldability, availability,temperature property, weatherability, and price should be dulyconsidered.

[0402] A moment activator to be mixed in the tape substrate may be aplurality of compounds selected from compounds containing a benzothiazylor benzothiazyl radical or a diphenylacrylate radical such asethyl-2-cyano-3,3-di-phenylacrylate.

[0403] Preferably, 10 to 200 parts by weight of a moment activator ismixed in 100 parts by weight of a tape substrate. If less than 10 partsby weight is mixed, the magnitude of dipole moment will not besufficiently improved, whereas if more than 200 parts by weight ismixed, the moment activator will be insufficiently blended with the tapesubstrate or may waken the mechanical integrity of the product.

[0404] To select an appropriate moment activator to be mixed in the tapesubstrate, not only the magnitude of dipole moment but also themiscibility between the moment activator and the tape substrate shouldbe appropriately considered, that is, the SP values of the two should beclose enough.

[0405] The magnitude of dipole moment is subject to the tape substratematerial and moment activator. Even if the same materials are used, themagnitude of dipole moment varies with the working temperature. Themagnitude of dipole moment is also affected by the magnitude of energytransferred to the tape substrate. Thus, the tape substrate material andmoment activator should be selected so as to provide the largestpossible magnitude of dipole moment considering the probable temperatureand magnitude of energy.

[0406] A filler such as mica scales, glass pieces, glass fibers, carbonfibers, calcium carbonate, barite, or precipitated barium sulfate may beadditionally provided in the tape substrate to further improve theimpact absorption capability and to increase the mechanical strength ofthe material. Preferably, 10 to 80% by weight of a filler is blended inthe tape substrate.

[0407] If less than 10% by weight is blended, the filler will notsufficiently improve the absorption capability, whereas if more than 80%by weight is blended, it will not be blended well or will reduce themechanical integrity of the tape product.

[0408] The grip tape of the present invention can be manufactured bymixing the tape substrate material and moment activator and optionally afiller such as a dispersant or thickener with conventionalmelting/mixing means such as a dissolver, Banbury mixer, planetarymixer, grain mill, open kneader, or vacuum kneader.

[0409] As described above, the moment activator is mixed in the tapesubstrate to significantly increase the magnitude of dipole moment andprovide an excellent impact absorption capability. The magnitude ofdipole moment in the tape substrate containing a moment activator isgiven as the difference in dielectric constant (∈′) between A and Bshown in FIG. 4. That is, the magnitude of dipole moment increases whenthe difference in dielectric constant (∈′) between A and B increases.

[0410]FIG. 4 is a graph showing a relationship between the dielectricconstant (∈′) and the dielectric loss factor (∈″). The relationshipbetween the dielectric constant (∈′) and the dielectric loss factor (∈″)is given as follows: Dielectric Loss Factor (∈″)=Dielectric Constant(∈′)×Dielectric Loss Tangent (tan δ).

[0411] Through research on grip tapes, the inventors have found that theenergy or impact absorption capability can be improved by increasing thedielectric loss factor (∈″).

[0412] The inventors have also found that the grip tape of the presentinvention provides excellent impact absorption when the dielectric lossfactor is 50 or greater at the frequency of 110 Hz.

[0413] The impact absorption material according to this invention can beused on shoe soles as well.

[0414] Conventional impact absorptive shoes use a foamed resin materialsuch as polyvinyl chloride or polyurethane in their shoe soles.

[0415] Due to the low impact absorption capability of such a foamedresin material, conventional shoe soles cannot not sufficiently dampimpact or shock.

[0416] Some conventional shoe soles utilize innersoles provided with twosheets put together to form a large number of cells filled with liquidsilicon, polyurethane, or rubber.

[0417] Although such shoe soles somewhat improve the impact absorptioncapability, the resultant shock absorption capability is still not highenough.

[0418] In addition, such shoe soles require a complicated structure andthe manufacturing cost is high.

[0419] The shoe sole according to this invention can appropriately copewith those shortcomings and can provide unexpectedly excellent impactabsorption.

[0420] The shoe 11 shown in FIG. 69 has under a shoe leather 12 amulti-layer shoe bottom 16 consisting of a thin and soft insole 13, amidsole 14 installed under the insole 13 of an impact absorptivematerial, and a wear-resistant outersole 15 installed under the midsole14.

[0421] The structure and shape of impact absorptive shoes using the shoesole according to this invention may be designed as desired depending onthe requirements.

[0422] The functions of the shoes can also be designed as desired, forexample by applying a wear-resistant and impact-absorptive material tothe outsole 15 of the shoe 11 as shown in FIG. 69 to improve the impactabsorption capability of the shoes.

[0423] An impact absorptive material containing a moment activator whichcan increase the amount of dipole moment in the base material is appliedon the shoe sole of this invention (the midsole 14 in the shoe 11 shownin FIG. 69).

[0424] The impact absorptive material to be used as the shoe sole is nowdescribed in detail. The base material of this impact absorptivematerial may be a polymer such as polyvinyl chloride, polyethylene,chlorinated polyethylene, polypropylene, ethylene-vinyl acetatecopolymer, polymethyl methacrylate, polyvinylidene fluoride,polyisoprene, polystyrene, styrene-butadiene-acrylonitrile copolymer,styrene-acrylonitrile copolymer, acrylonitrile-butadiene rubber (NBR),styrene-butadiene rubber (SBR), butadiene rubber (BR), natural rubber(NR), isoprene rubber (IR), or their selected mixture. Polyvinylchloride is preferred for its moldability and low cost.

[0425] In the impact absorption base material of such a polymer, therelationship between the magnitude of dipole moment and the impactabsorption capability is as follows. The general mechanism of impactabsorption in the impact absorption material is that impact such asvibration collides against the shoe sole (the impact absorptivematerial) to be partially converted into heat. That is, the impactenergy is converted into heat and damped. Through research on themechanism of the impact absorption of impact absorptive materials usedas shoe soles, the inventors have found that the displacement andrecovery of the dipoles in the impact absorptive material (basematerial) provides great energy damping.

[0426] The details are given below. FIG. 1 shows an arrangement ofdipoles 12 in an impact absorptive material (base material) 11 prior tothe propagation of impact. The arrangement of the dipoles 12 is stablethere. When an impact is applied onto the base material, the dipoles 12present in the impact absorptive material 11 are displaced into anunstable state such as shown in FIG. 2, which are then prompted toreturn to a stable state such as shown in FIG. 1.

[0427] Energy is then absorbed and damped. The impact absorptioncapability is assumed to be provided through the absorption of energy bythe displacement and recovery of the dipoles in the impact absorptivematerial 11.

[0428] Based on this mechanism of impact absorption, the impactabsorption capability of the impact absorptive material 11 can beimproved by increasing the magnitude of dipole moment in the impactabsorptive material 11. Thus, a polymer inherently having a largemagnitude of dipole moment in the molecules can be advantageously usedto provide a better impact absorption capability.

[0429] Polymers which inherently have large dipole moment may be apolarity polymer such as polyvinyl chloride, chlorinated polyethylene,acrylic rubber (ACR), acrylonitrile-butadiene rubber (NBR),styrene-butadiene rubber (SBR), or chloroprene rubber (CR).

[0430] The shoe sole according to this invention (midsole 14 shown inFIG. 69) is expected to be used within the temperature range betweenabout −20 C. and about 40 C. It is advantageous to use a polymer whichhas or will have a glass transition point in this operating temperatureregion because the impact absorption capability is maximized near theglass transition point of the polymer according to the inventors'experiment.

[0431] Polymers which will have a glass transition point in theoperating temperature region may be polyvinyl chloride, polyethylene,polypropylene, ethylene-vinyl acetate copolymer, polymethylmethacrylate, polystyrene, or styrene-butadiene-acrylonitrile copolymer,to which a plasticizer such as di-2-ethylhexalphthalate (DOP),dibutylphthalate (DBP), or diisononylphthalate (DINP) is added to shifttheir glass transition point (Tg) into the operating temperature region,or polymers such as acrylic rubber (ACR), acrylonitrile-butadiene rubber(NBR), styrene-butadiene rubber (SBR), butadiene rubber (BR), naturalrubber (NR), isoprene rubber (IR), chloroprene rubber (CR), andchlorinated polyethylene which themselves have a glass transition point(Tg) in the operating temperature region.

[0432] In selecting an appropriate base material, not only the magnitudeof dipole moment in the polymer and the operating temperature region butalso usability, moldability, availability, temperature property,weatherability, and price should be appropriately considered.

[0433] The moment activator to be mixed in the impact absorptivematerial for shoe soles can be a plurality of compounds containing abenzothiazyl or benzothiazyl radical or a diphenylacrylate radical suchas ethyl-2-cyano-3,3-di-phenylacrylate.

[0434] Preferably, 10 to 200 parts by weight of a moment activator ismixed in 100 parts by weight of a base material. If less than 10 partsby weight of a moment activator is mixed, the magnitude of dipole momentwill not be sufficiently increased, whereas if more than 200 parts byweight is mixed, the moment activator will insufficiently blend with thebase material and will provide a poor mechanical strength.

[0435] To select an appropriate moment activator to be mixed in the basematerial, not only the magnitude of dipole moment but also themiscibility between the moment activator and the base material should beduly considered, that is, the SP values of both should be close enough.

[0436] The magnitude of dipole moment is subject to the base materialand moment activator. Even if the same materials are used, the magnitudeof dipole moment varies with the temperature. The magnitude of dipolemoment is also affected by the magnitude of energy transferred to thebase material. Thus, the base material and moment activator should beselected so as to provide the largest possible magnitude of dipolemoment considering the expected temperature and magnitude of energy.

[0437] A filler such as mica scales, glass pieces, glass fibers, carbonfibers, calcium carbonate, barite, or precipitated barium sulfate can beadditionally blended in the base material to further improve theabsorption capability and as well as the mechanical integrity of thematerial. Preferably, 10 to 80% by weight of a filler is blended in thebase material. If less than 10% by weight of a filler is blended, theaddition of the filler will not sufficiently improve the absorptioncapability, whereas if more than 80% by weight of a filler is blended,it will not blend well in the base material and will reduce themechanical strength of the product.

[0438] The impact absorptive material used as the shoe sole of thepresent invention can be manufactured by mixing the base material andmoment activator and optionally a filler, dispersant, or thickener asdesired using a conventional melting and mixing apparatus such as adissolver, Banbury mixer, planetary mixer, grain mill, open kneader, orvacuum kneader.

[0439] As described above, the moment activator is mixed in the basematerial to significantly increase the magnitude of dipole moment inorder to provide an excellent impact absorption capability.

[0440] The magnitude of dipole moment in the impact absorptive materialcontaining the moment activator in its base material is given as thedifference in dielectric constant (∈′) between A and B shown in FIG. 4.

[0441] That is, the magnitude of dipole moment increases as thedifference in dielectric constant (∈′) between A and B increases.

[0442]FIG. 4 is a graph showing a relationship between the dielectricconstant (∈′) and the dielectric loss factor (∈″). The relationshipbetween the dielectric constant (∈′) and the dielectric loss factor (∈″)is given as follows: Dielectric Loss Factor (∈″)=Dielectric Constant(∈′)×Dielectric Loss Tangent (tan δ).

[0443] Through lengthy research on impact absorptive materials used asshoe soles, the inventors have found that the energy or impactabsorption capability can be improved by increasing the dielectric lossfactor (∈″).

[0444] Studying the dielectric loss factor (∈″) of the above impactabsorptive materials, the inventors have also found that the materialsprovide excellent impact absorption when the dielectric loss factor is50 or larger at the frequency of 110 Hz.

[0445] In the following is a description of electromagnetic waveabsorptive materials according to the present invention.

[0446] Metal sheets have been conventionally used to blockelectromagnetic waves coming from electronic devices. Due to massproduction and for cost reduction, plastic materials that passelectromagnetic waves are concurrently in use as housings for electronicdevices, resulting in leakage of electromagnetic waves.

[0447] Various attempts have been made to prevent electromagnetic wavesfrom leaking. For example, sheet-like electromagnetic wave absorptivematerials are provided by sintering and molding ferrite powders.

[0448] Such electromagnetic wave absorptive sheets do not providesufficient electromagnetic wave absorption. They are hard to process ormold, and are fragile and unsuitable for mass production.

[0449] To solve such shortcomings, ferrite powders are mixed with aresin material. However, the electromagnetic wave absorption capabilityof such a material is still insufficient, and the ferrite powders have apoor miscibility with a polymer due to their relatively large surfacearea. As a result, the product will be very fragile.

[0450] Carbon powders or titanic acid alkali earth metal powders arealso used instead of ferrite powders, but their electromagnetic waveabsorptive characteristics are still insufficient.

[0451] The electromagnetic wave absorptive materials according to thisinvention can appropriately solve these technical problems ofconventional electromagnetic wave absorptive materials. The material ofthe present invention provides excellent electromagnetic waveabsorption, and is sufficiently sturdy and easy to process.

[0452] The base material of such an electromagnetic wave absorber of thepresent invention may be a polymer such as polyvinyl chloride,chlorinated polyethylene, polyethylene, polypropylene, ethylene-vinylacetate copolymer, polymethyl methacrylate, polystyrene,styrene-butadinene-acrylonitrile copolymer, polyurethane,polyvinylformal, epoxy, phenol, urea, or silicon, or rubber polymer suchas acryl rubber (ACR), acrylonitrile-butadinene rubber (NBR),styrene-butadinene rubber (SBR), butadiene rubber (BR), natural rubber(NR), isoprene rubber (IR), Or chloroprene rubber (CR).

[0453] The electromagnetic wave absorptive material or absorber of thepresent invention contains a moment activator which can increase themagnitude of dipole moment in the base material. The relationshipbetween the magnitude of dipole moment and the electromagnetic waveabsorption capability is described below. Electromagnetic waves arepropagation of vibration through an electromagnetic field in a vacuum ormatter. The general mechanism of electromagnetic wave absorption in theelectromagnetic wave absorptive material is that electromagnetic wavescollide against the electromagnetic wave absorptive material to bepartially converted into heat. The vibration of electromagnetic fieldsis damped through this energy conversion. Through research on themechanism of electromagnetic wave absorption, the inventors have foundthat the displacement and recovery of the dipoles in the base materialconstituting the electromagnetic wave absorber significantly promotesthe energy conversion.

[0454] The detail is given below. FIG. 1 shows a representativearrangement of dipoles 12 in a base material 11 prior to the propagationof electromagnetic waves (vibration of electromagnetic fields).

[0455] The dipoles 12 are held stable there. When electromagnetic wavespropagate and displace the dipoles 12 in the base material 11, thedipoles 12 are displaced into an unstable state such as shown in FIG. 2,which are prompted to return to a stable state such as shown in FIG. 1.

[0456] Energy is then absorbed or converted. The electromagnetic waveabsorption capability of the present invention is assumed to be providedthrough this conversion of energy provided by the displacement andrecovery of the dipoles in the base material 11.

[0457] Based on this mechanism of electromagnetic wave absorption, theelectromagnetic wave absorption capability of the base material 11 canbe improved by increasing the magnitude of dipole moment in the basematerial 11. Thus, it is essential to use a base material whichinherently has large dipole moment in the molecules in order to provideimproved electromagnetic wave absorption.

[0458] Polymers inherently having a large magnitude of dipole moment maybe a polarity polymer such as polyvinyl chloride, chlorinatedpolyethylene, acrylic rubber (ACR), acrylonitrile-butadiene rubber(NBR), styrene-butadiene rubber (SBR), or chloroprene rubber (CR). Sucha polarity polymer is also very strong and easy to process.

[0459] The electromagnetic wave absorptive material according to thisinvention can be used for electronics appliances, and it is essential tomaximize the electromagnetic wave absorption characteristic at workingtemperatures or between about −20 C. and about 40 C.

[0460] To maximize the electromagnetic wave absorption in the operatingtemperature region, the electromagnetic wave absorptive materialaccording to this invention uses as its base material a polymer whichhas or will have a glass transition point in the operating temperatureregion, such as polyvinyl chloride, chlorinated polyethylene,polyethylene, polypropylene, ethylene-vinyl acetate copolymer,polymethyl methacrylate, polystyrene, or styrene-butadiene-acrylonitrilecopolymer, to which a plasticizer such as di-2-ethylhexalphthalate(DOP), dibutylphthalate (DBP), or diisononylphthalate (DINP) is added toshift their glass transition point (Tg) into the operating temperatureregion of −20 C. to 40 C., or a rubber polymer such as acrylic rubber(ACR), acrylonitrile-butadiene rubber (NBR), styrene-butadiene rubber(SBR), butadiene rubber (BR), natural rubber (NR), isoprene rubber (IR),chloroprene rubber (CR), or chlorinated polyethylene, which themselveshave a glass transition point (Tg) in the operating temperature regionof −20 C. to 40 C.

[0461] In selecting an appropriate polymer for a base material, not onlythe magnitude of dipole moment in the molecules and the operatingtemperature region but also strength and easiness to process, usability,moldability, availability, temperature property, weatherability, andprice should be duly considered.

[0462] The moment activator to be mixed in the base material may be aplurality of compounds selected from ones containing a benzothiazyl orbenzotriazole radical or a diphenylacrylate radical such asethyl-2-cyano-3,3-di-phenylacrylate.

[0463] Preferably, 10 to 200 parts by weight of a moment activator ismixed in 100 parts by weight of a base material. If less than 10 partsby weight of a moment activator is mixed, the addition will not providea sufficient increase of dipole moment, whereas if more than 200 partsby weight is mixed, the moment activator will not sufficiently mix withthe polymer constituting the base material.

[0464] To select an appropriate moment activator to be mixed in the basematerial, the miscibility between the moment activator and the polymerof the base material should be appropriately considered, that is, the SPvalues of the both should be close enough.

[0465] The magnitude of dipole moment is subject to the base materialand the moment activator blended therewith. The magnitude of dipolemoment also varies with the working temperature as well as is affectedby the magnitude of energy transferred to the base material. Thus, thebase material and the moment activator should be selected so as toprovide the largest possible amount of dipole moment considering theexpected temperature and magnitude of energy.

[0466] As described above, the electromagnetic wave absorptive materialcontaining a moment activator provides excellent electromagnetic waveabsorption. The magnitude of dipole moment in the electromagnetic waveabsorptive material (base material) is represented as the difference indielectric constant (∈′) between A and B shown in FIG. 4. That is, themagnitude of dipole moment increases as the difference in dielectricconstant (∈′) between A and B increases.

[0467]FIG. 4 is a graph showing a relationship between the dielectricconstant (∈′) and the dielectric loss factor (∈″). The relationshipbetween the dielectric constant (∈′) and the dielectric loss factor (∈″)is given as follows: Dielectric Loss Factor (∈″)=Dielectric Constant(∈′)×Dielectric Loss Tangent (tan δ).

[0468] Through research on electromagnetic wave absorptive materials,the inventors have found that the energy absorption capability orelectromagnetic wave absorption capability can be improved by increasingthe dielectric loss factor (∈″).

[0469] The inventors have also found that the material of the inventionprovides excellent electromagnetic wave absorption when the dielectricloss factor is 100 or larger at the frequency of 110 Hz.

[0470] Since different electromagnetic frequency regions need be copedwith, it is essential to provide particularly favorable electromagneticwave absorption characteristics in particular frequency ranges. To meetthis requirement, the electromagnetic wave absorptive material of thepresent invention contains a base material moment activator which isappropriately selected. Different base materials and moment activatorsexhibit different electromagnetic wave absorption characteristics indifferent frequency regions. Accordingly, a base material and a momentactivator which exhibit high electromagnetic wave absorption indifferent electromagnetic frequency regions should be selected and used.

[0471] There is a demand for a single electromagnetic wave damper whichcan effectively cover a wide frequency region. Such a requirement can bemet by combining together a plurality of different types ofelectromagnetic wave absorptive materials having different frequencyproperties, or blending different moment activators exhibiting differentpeak electromagnetic wave absorption properties in different frequencyregions with a plurality of different base materials exhibitingdifferent frequency characteristics, or blending a plurality ofdifferent types of moment activator compounds exhibiting differentfrequency properties with a base material.

[0472] Such a combined type absorber may be provided, for example, bycombining a sheet material having a peak property in a frequency rangeof 500 60 1,000 MHz with a sheet material having a peak property in afrequency range of 1,000 to 2,000 MHz to obtain a combined type sheetmaterial by lamination or integration. Thus, an electromagnetic waveabsorber sheet which exhibits an effective electromagnetic waveabsorption characteristic in the frequency range between 500 and 2,000MHz can be obtained.

[0473] A moment activator or compound exhibiting an effectiveelectromagnetic wave absorption characteristic in the frequency rangebetween 500 to 1,000 MHz and a moment activator or compound exhibitingan effective electromagnetic wave absorption characteristic in thefrequency range between 1,000 to 2,000 MHz may be blended in a basematerial, which is molded into a sheet. Thus, an electromagnetic waveabsorptive sheet exhibiting an effective electromagnetic wave absorptioncharacteristic in the frequency range between 500 and 2,000 MHz can beobtained. This embodiment absorber can be a single sheet and does notrequire lamination or adhesion.

[0474] The electromagnetic wave absorptive material according to thisinvention may be used as a composite comprising a synthetic resin filmsuch as of polyvinyl chloride, polyethylene, polypropylene, orpolyethylene, or a fibrous sheet such as paper, cloth, or non-wovencloth.

[0475] The electromagnetic wave absorptive material or absorber of thepresent invention may be provided as an electromagnetic wave absorptivepaint.

[0476] Conventional electromagnetic wave absorptive paints contain metalpowders such as ferrite or titanic acid alkali earth metal or inorganicpowders such as carbon powders.

[0477] Such conventional electromagnetic wave absorptive paints have aninsufficient electromagnetic absorption capability and require a largeamount of inorganic powders to be mixed therein to provide effectiveelectromagnetic wave absorption. Furthermore, to provide sufficientelectromagnetic wave absorption, the electromagnetic wave absorptivelayer need be 20 to 30 mm thick. Such an electromagnetic wave absorberis heavy and may be removed easily from the application site. All thesedefects are detrimental factors for applications on electronics,communication apparatuses, or airplanes.

[0478] The electromagnetic wave absorptive paint according to thisinvention can adequately solve these technical problems. It can providea thin and light electromagnetic wave absorptive layer which is capableof providing highly effective electromagnetic wave absorption.

[0479] The electromagnetic wave absorptive paint of the presentinvention contains a moment activator which can increase the amount ofdipole moment.

[0480] The relationship between the magnitude of dipole moment and theelectromagnetic wave absorption capability is described below. As iswell known, electromagnetic waves are vibrations in electromagneticfields through a vacuum or matter. Electromagnetic waves collide againstan electromagnetic wave absorptive layer to be partially converted intoheat, providing an energy conversion or damping.

[0481] Through research, the inventors have found that the displacementand recovery of the dipoles in the electromagnetic wave absorptive paintprovides additional and excellent energy absorption.

[0482] The details are given below. FIG. 1 shows an arrangement ofdipoles 12 in an electromagnetic wave absorptive layer (base material)11 provided by the electromagnetic wave absorptive paint of the presentinvention prior to the propagation of electromagnetic waves. The dipoles12 are stable. When electromagnetic waves propagate and displace thedipoles 12 in the electromagnetic wave absorptive layer 11, the dipoles12 are displaced into an unstable state such as shown in FIG. 2, whichare prompted to return to a stable state such as shown in FIG. 1.

[0483] Energy is then absorbed or consumed. The electromagnetic waveabsorption capability is assumed to be provided through this absorptionor conversion of energy provided by the displacement and recovery of thedipoles in the electromagnetic wave absorptive layer 11.

[0484] The paint base material may be a polymer such as polyvinylchloride, chlorinated polyethylene, polyethylene, polypropylene,ethylene-vinyl acetate copolymer, polymethyl methacrylate, polystyrene,styrene-butadinene acrylonitrile copolymer, polyurethane,polyvinylformal, epoxy, phenol, urea, or silicon, or rubber polymer suchas acryl rubber (ACR), acrylonitrile-butadiene rubber (NBR),styrene-butadiene rubber (SBR), butadiene rubber (BR), natural rubber(NR), isoprene rubber (IR), or chloroprene rubber (CR).

[0485] Based on the above mechanism of electromagnetic wave absorption,the electromagnetic wave absorption capability of the electromagneticwave absorptive layer 11 can be improved by increasing the amount ofdipole moment in the electromagnetic wave absorptive layer 11.

[0486] Accordingly, a polymer inherently having large dipole moment inthe molecules may be advantageously used to provide highly effectiveelectromagnetic wave absorption.

[0487] Polymers which inherently have large dipole moment may bepolarity polymers such as polyvinyl chloride, chlorinated polyethylene,acrylic rubber (ACR), acrylonitrile-butadiene rubber (NBR),styrene-butadiene rubber (SBR), and chloroprene rubber (CR).

[0488] The electromagnetic wave absorptive paint according to thisinvention is applicable on electronics, communication apparatuses,vehicles, airplanes, interior materials, or electric appliances, so itis very important to maximize the electromagnetic wave absorptionproperty at operating temperatures between about −20 C. and about 40 C.

[0489] To maximize the electromagnetic wave absorption in the operatingtemperature region, this invention proposes that the electromagneticwave absorptive paint comprise a polymer which has or will have a glasstransition point in the operating temperature region. A polymer whichwill have a glass transmission point in the operating temperature regionmay be polyvinyl chloride, polyethylene, polypropylene, ethylene-vinylacetate copolymer, polymethyl methacrylate, polystyrene, orstyrene-butadiene-acrylonitrile copolymer, to which a plasticizer suchas di-2-ethylhexalphthalate (DOP), dibutylphthalate (DBP), ordiisononylphthalate (DINP) is added to shift their glass transitionpoint (Tg) into the operating temperature region of −20 C. to 40 C., ora rubber polymer such as acrylic rubber (ACR), acrylonitrile-butadienerubber (NBR), styrene-butadiene rubber (SBR), butadiene rubber (BR),natural rubber (NR), isoprene rubber (IR), chloroprene rubber (CR), orchlorinated polyethylene which themselves have a glass transition point(Tg) in the operating temperature region of −20 C. to 40 C.

[0490] In selecting an appropriate paint base material, not only themagnitude of dipole moment in the molecules and the operatingtemperature region but also usability, moldability, availability,temperature property, weatherability, and price should be dulyconsidered.

[0491] The moment activator may be a plurality of compounds selectedfrom ones containing a benzothiazyl or benzothiazyl radical or onescontaining a diphenylacrylate radical such as ethyl-2-cyano-3,3di-phenylacrylate.

[0492] Preferably, 10 to 200 parts by weight of a moment activator ismixed in 100 parts by weight of a paint base material. If less than 10parts by weight of a moment activator is mixed, the dipole moment willnot be sufficiently promoted, whereas if more than 200 parts by weightof a moment activator is mixed, the miscibility of the moment activatorwith the base paint material will be a problem and will not providesufficient strength.

[0493] To select an adequate moment activator to be mixed in the paintbase, the miscibility between the moment activator and the paint basematerial should be adequately considered. That is, the SP values of bothshould be close enough.

[0494] The magnitude of dipole moment is subject to the paint basematerial and moment activator. The same components will not provide thesame magnitude of dipole moment under different temperature conditions.

[0495] The magnitude of dipole moment is also affected by the magnitudeof energy transferred to the paint. Accordingly, the paint base andmoment activator should be selected so as to provide the largestpossible magnitude of dipole moment, considering the expectedtemperature and magnitude of energy.

[0496] An electromagnetic wave absorptive paint should advantageously bealso workable in various electromagnetic frequency regions, so it isdesirable to provide an electromagnetic wave absorptive paint which caneffectively cover a wide frequency range. To meet this requirement, theelectromagnetic wave absorptive paint may comprise a plurality ofdifferent paint base materials and moment activator compounds. Differenttypes of paint base materials and moment activators exhibit differentabsorption characteristics in different frequency regions, which incombination can provide a wide range of electromagnetic wave absorption.

[0497] There is a demand for an electromagnetic wave absorber workableover a wide frequency range. Such a requirement is met by mixing aplurality of paint base materials and moment activator compoundsexhibiting different electromagnetic wave absorption characteristics indifferent frequency regions.

[0498] A moment activator which effectively provides electromagneticwave absorption in the frequency region between 500 to 1,000 MHz may bemixed in a paint base material which provides effective electromagneticwave absorption in the frequency region between 1,000 to 2,000 MHz.Consequently, an electromagnetic absorptive layer provided with thiselectromagnetic wave absorptive paint provides effective electromagneticwave absorption in the frequency range between 500 to 2,000 MHz.

[0499] A moment activator compound providing peak electromagnetic waveabsorption in the frequency range between 500 to 1,000 MHz and a momentactivator compound providing peak electromagnetic wave absorption in thefrequency range between 1,000 to 2,000 MHz may be mixed in a paint basematerial. Consequently, the electromagnetic wave absorptive layer canprovide effective electromagnetic wave absorption in the frequency rangebetween 500 and 2,000 MHz.

[0500] A filler such as mica scales, glass pieces, glass fibers, carbonfibers, calcium carbonate, barite, or precipitated barium sulfate can beadditionally blended in the paint material to further improveelectromagnetic wave absorption capability and provide the paint filmwith strength. Preferably, 10 to 90% by weight of a filler is blended inthe paint material.

[0501] If less than 10% by weight of a filler is blended, the additionof the filler will not sufficiently improve the absorption capability,whereas if more than 90% by weight of a filler is blended, the fillerwill not blend sufficiently and will reduce the integrity of the paintlayer.

[0502] The electromagnetic wave absorptive paint according to thisinvention may be obtained in an emulsion form by mixing together thepaint material and moment activator and optionally a filler or fillers,and dispersing the mixture in water or alcohol. Dispersant, wettingagent, thickener, antifoaming agent, or colorant may be further added asdesired.

[0503] Such an electromagnetic wave absorptive paint of the presentinvention may be manufactured by mixing the paint base material andmoment activator and a dispersing solvent such as water or alcohol aswell as a filler, dispersant, or thickener as required, and dispersingand blending the mixture using conventional melting and mixing meanssuch as a dissolver, Banbury mixer, planetary mixer, grain mill, openkneader, or vacuum kneader.

[0504] The electromagnetic wave absorptive paint may be applied by aconventional air spray gun, airless spray gun, or brushing.

[0505] As described above, the moment activator is mixed in the paintmaterial to significantly increase the magnitude of dipole moment inorder to provide an excellent electromagnetic wave absorption capabilityfor the electromagnetic wave absorptive layer.

[0506] The magnitude of dipole moment in the electromagnetic waveabsorptive layer is defined as the difference in dielectric constant(∈′) between A and B shown in FIG. 4. The magnitude of dipole momentincreases as the difference in dielectric constant (∈′) between A and Bincreases.

[0507]FIG. 4 is a graph showing a relationship between the dielectricconstant (∈′) and the dielectric loss factor (∈″). The relationshipbetween the dielectric constant (∈′) and the dielectric loss factor (∈″)is given as follows: Dielectric Loss Factor (∈″)=Dielectric Constant(∈′)×Dielectric Loss Tangent (tan δ).

[0508] Through research on electromagnetic wave absorptive paints, theinventors have found that the energy absorption capability or theelectromagnetic wave absorption capability can be improved by increasingthe dielectric loss factor (∈″).

[0509] The inventors have also found that the paint provides excellentelectromagnetic wave absorption when the dielectric loss factor is 100or larger at the frequency of 110 Hz.

[0510] A vibration-proof material according to this invention is nowdescribed.

[0511] Rubber materials such as butyl rubber and NBR, which can beeasily processed and possess sufficient mechanical strength, have beenused as conventional vibration-proofing materials.

[0512] The vibration shielding capability (vibration-energy insulationor reduction capability) of such a rubber material is excellent,however, it is not high enough when used singly. Thus, for a vibrationshielding of buildings and equipment, such a rubber material has beenused in a composite form such as a laminate with steel plates or in acombination of such a laminate with a lead core or oil damper, whichplastically deforms to absorb vibration energy.

[0513] Since such a conventional rubber material used as a vibrationshield need be used in a composite form to provide sufficient vibrationdamping, its vibration-proof structure necessarily becomes complicated,so there has been a demand for an improved vibration-proof material.

[0514] Japanese Patent Laid-Open Publication No. 2-308835 and JapanesePatent Laid-Open Publication No. 2-34643 have proposed rubbercompositions with improved vibration-proof capabilities.

[0515] Those disclosed rubber compositions, however, require a largeamount of carbon, for example, 40 to 50 parts by weight of carbon blackto be mixed in 100 parts by weight of a rubber material in order toprovide high enough vibration shield, resulting in significantly reducedtensile strength and creep resistance.

[0516] The vibration-proof material according to this invention canappropriately solve these technical problems and provide improvedvibration shield, which is mechanically strong and easy to process.

[0517] The vibration shielding material of the present inventioncontains in its base material a moment activator which can increase themagnitude of dipole moment in an amount 10 to 300 parts by weight in 100parts by weight of the base material.

[0518] First, the relationship between the magnitude of dipole momentand the vibration-proof capability is described. FIG. 1 shows anarrangement of dipoles 12 in a base material 11 prior to the transfer ofvibration energy. Those dipoles 12 are stable. When a vibration energyis transferred and displaces the dipoles 12 in the base material 11 intoan unstable state such as shown in FIG. 2, the dipoles 12 are promptedto return to a stable state such as shown in FIG. 1.

[0519] Energy is then consumed. The vibration-proof capability isassumed to be provided through the consumption of energy provided by thedisplacement and recovery of the dipoles in the base material 11.

[0520] The vibration shielding capability of the base material 11 can beimproved by increasing the magnitude of dipole moment in the basematerial 11. Thus, the base material should be one which inherently haslarge dipole moment in the molecules to provide an improvedvibration-proof capability.

[0521] Polymers which inherently have large dipole moment may be apolarity polymer such as polyvinyl chloride, chlorinated polyethylene,acrylic rubber (ACR), acrylonitrile-butadiene rubber (NBR),styrene-butadiene rubber (SBR), or chloroprene rubber (CR).

[0522] Such a polarity polymer is mechanically strong and easy toprocess. The vibration damping material according to this invention canbe applied on automobiles, interior materials, construction materials,and electric appliances, so it is essential to maximize thevibration-energy shielding at operating temperatures between about −20C. and about 40 C.

[0523] To maximize the vibration-energy absorption capability in theoperating temperature region, this invention proposes that the vibrationshielding material comprise as its base material a polymer which has orwill have a glass transition point in the operating temperature region.Polymers which will have a glass transmission point in the operatingtemperature range may be polyvinyl chloride, polyethylene,polypropylene, ethylene-vinyl acetate copolymer, polymethylmethacrylate, polyvinylidene fluoride, polyisoprene, polystyrene,styrene-butadiene-acrylonitrile copolymer, or styrene-acrylonitrilecopolymer, to which a plasticizer such as di-2-ethylhexalphthalate(DOP), dibutylphthalate (DBP), or diisononylphthalate (DINP) is added toshift their glass transition point (Tg) into the operating temperatureregion of −20 C. to 40 C, or a rubber polymer such as acrylic rubber(ACR), acrylonitrile-butadiene rubber (NBR), styrene-butadiene rubber(SBR), butadiene rubber (BR), natural rubber (NR), isoprene rubber (IR),chloroprene rubber (CR), or chlorinated polyethylene which themselveshave a glass transition point (Tg) in the operating temperature regionof −20 C. to 40 C.

[0524] In selecting an appropriate polymer for the base material, notonly the magnitude of dipole moment in the molecules and the operatingtemperature region but also usability, moldability, availability,temperature property, weatherability, and price should be dulyconsidered.

[0525] The moment activator may be a plurality of compounds selectedfrom ones containing a benzothiazyl or benzothiazyl radical orcontaining a diphenylacrylate radical such asethyl-2-cyano-3,3-di-phenylacrylate.

[0526] 10 to 300 parts by weight of a moment activator is mixed in 100parts by weight of a base material. If less than 10 parts by weight of amoment activator is mixed, the addition of the moment activator will notsufficiently increase the magnitude of dipole moment, whereas if morethan 300 parts by weight of a moment activator is mixed, the momentactivator will not sufficiently blend with the base material.

[0527] To select an appropriate moment activator to be mixed in the basematerial, the miscibility between the moment activator and the basematerial should be duly considered. That is, the SP values of bothshould be close enough.

[0528] The magnitude of dipole moment is subject to the base materialand moment activator. Even if they are the same, the magnitude of dipolemoment varies with the working temperature. The magnitude of dipolemoment is also affected by the magnitude of vibration energy transferredto the base material. Thus, the base material and moment activatorshould be selected so as to provide the largest possible magnitude ofdipole moment, considering the possible temperature and magnitude ofvibration energy.

[0529] A filler such as mica scales, glass pieces, glass fibers, carbonfibers, calcium carbonate, barite, or precipitated barium sulfate can beadditionally blended in the base material to further improve thevibration-proof capability.

[0530] The vibration damping material according to this invention can beobtained by mixing together the base material and moment activator, andoptionally a filler or fillers. They can be made into various forms suchas sheets, blocks, grains, or fibers depending on applications or useconditions. The size or shape of the vibration-proof material may becontrolled to provide different resonance frequency properties and maythus be determined as appropriate depending on applications or useconditions.

[0531] As described above, the vibration shielding material of thepresent invention provides an excellent vibration-proof capability.

[0532] The magnitude of dipole moment in the vibration absorptivematerial is represented as the difference in dielectric constant (∈′)between A and B shown in FIG. 4. The magnitude of dipole momentincreases as the difference in dielectric constant (c′) between A and Bincreases.

[0533]FIG. 4 is a graph showing a relationship between the dielectricconstant (∈′) and the dielectric loss factor (∈″). The relationshipbetween the dielectric constant (∈′) and the dielectric loss factor (∈″)is given as follows: Dielectric Loss Factor (∈″)=Dielectric Constant(∈′)×Dielectric Loss Tangent (tan δ).

[0534] Through research on vibration absorptive materials, the inventorshave found that the vibration-proof capability (ξ) can be improved byincreasing the dielectric loss factor (∈″). That is, the dielectric losstangent (tan δ) indicating an electronic property of polymerscorresponds to the elastic tangent (tan δ) indicating dynamicelasticity, and the relationship between the elastic tangent (tan δ) andthe vibration-proof ratio (ξ) indicating the level of thevibration-proofing capability is expressed as follows:ξ=tan δ/2.

[0535] The inventors have also found that with a dielectric loss factorof 50 or larger at the frequency of 110 Hz, the material has a highelastic tangent (tan δ) or high damping ratio (ξ), which is inproportion to the elastic tangent (tan δ), and can provide excellentvibration shield.

[0536] A piezoelectric material according to this invention is nowdescribed.

[0537] A conventional piezoelectric material is formed by sintering apiezoelectric ceramic such as lead zirconate titanate (PZT) or bariumtitanate and polarization of the ceramic.

[0538] Such a piezoelectric material is fragile and hard to process overa large area. Besides, piezoelectric materials are generally expensive.

[0539] Another type of piezoelectric polymer is provided by drawing afluorine resin such as PVDF and polarization thereof.

[0540] Although its fragile nature is improved, this piezoelectricmaterial provides poorer performance than the piezoelectric ceramic andis more expensive due to the need for drawing and polarizationprocesses.

[0541] Yet another piezoelectric material has been proposed, which is acomposite material formed by combining the piezoelectric ceramic with apiezoelectric polymer.

[0542] Even this piezoelectric material cannot eliminate thedisadvantages of the above conventional piezoelectric materials.

[0543] The piezoelectric material according to this invention canappropriately solve these technical weaknesses and does not requiredrawing or polarization treatment. Furthermore, the material of thepresent invention is relatively inexpensive but has an excellentpiezoelectric property.

[0544] The piezoelectric material of the present invention ischaracterized in that a moment activator is blended in its base materialto increase the magnitude of dipole moment therein.

[0545] The base material of this piezoelectric material may be a polymersuch as polyvinyl chloride, polyethylene, chlorinated polyethylene,polypropylene, ethylene-vinyl acetate copolymer, polymethylmethacrylate, polyvinylidene fluoride, polyisoprene, polystyrene,styrene-butadiene-acrylonitrile copolymer, styrene-acrylonitrilecopolymer, acrylonitrile-butadiene rubber (NBR), styrene-butadienerubber (SBR), butadiene rubber (BR), natural rubber (NR), isoprenerubber (IR), or their selected mixture. Polyvinyl chloride is preferredfor its moldability and low cost.

[0546] In the piezoelectric material comprising such a polymer as itsbase material, the relationship between the magnitude of dipole momentand the piezoelectric property is as follows. As is well known, when astress is applied onto the piezoelectric material, opposite electriccharges appear at the opposite surfaces of the piezoelectric material.The magnitude of the charges is in proportion to the stress. Whenelectric fields are applied to the piezoelectric material, distortionoccurs. Its magnitude is in proportion to the electric fields. It isalso known that a piezoelectric material consisting of a polymerproduces a piezoelectric effect through polarization caused by thefreezing of the orientation of the dipole moment in the main and sidechains of the polymer.

[0547] This characteristic is provided through energy conversion. Whilestudying the mechanism of the piezoelectric property of thepiezoelectric material, the inventors have found that the dipoles in thepiezoelectric material can be displaced with certain freedom and thenrecovered to a stable state, consuming energy and providing an excellentpiezoelectric performance.

[0548] Further details are given below. FIG. 1 shows an arrangement ofdipoles 12 in a piezoelectric base material 11 prior to the propagationof energy (stress). The dipoles 2 are stable. When an energy propagatesand displaces the dipoles 12 in the piezoelectric material 11, thedipoles 12 in the piezoelectric material 11 are displaced into anunstable state such as shown in FIG. 2, which are then prompted toreturn to a stable state such as shown in FIG. 1.

[0549] Energy is then effectively converted. The extra piezoelectricproperty is assumed to be provided through the conversion of energyprovided by the displacement and recovery of the dipoles in thepiezoelectric material 11.

[0550] The piezoelectric property can be improved by increasing theamount of dipole moment in the piezoelectric material (the basematerial) 11.

[0551] Accordingly, a polymer material inherently having large dipolemoment should advantageously be selected to provide a high piezoelectriccapacity.

[0552] Polymers which inherently have large dipole moment are polaritypolymers such as polyvinyl chloride, chlorinated polyethylene, acrylicrubber (ACR), acrylonitrile-butadiene rubber (NBR), styrene-butadienerubber (SBR), and chloroprene rubber (CR).

[0553] When applied to a sensor, the piezoelectric material of thepresent invention is subjected to temperatures between about −20 C. andabout 40 C. It is advantageous to use as the base material a polymerwhich has or will have a glass transition point in this operatingtemperature region because the piezoelectric capacity is maximized nearthe glass transition point of polymers.

[0554] Polymers which will have a glass transmission point in thisoperating temperature range may be polyvinyl chloride, polyethylene,polypropylene, ethylene-vinyl acetate copolymer, polymethylmethacrylate, polystyrene, or styrene-butadiene-acrylonitrile copolymer,to which a plasticizer such as di-2-ethylhexylphthalate (DOP),dibutylphthalate (DBP), or diisononylphthalate (DINP) is added to shifttheir glass transition point (Tg) into the operating temperature region,or a rubber polymer such as acrylic rubber (ACR),acrylonitrile-butadiene rubber (NBR), styrene-butadiene rubber (SBR),butadiene rubber (BR), natural rubber (NR), isoprene rubber (IR),chloroprene rubber (CR), or chlorinated polyethylene, which themselveshave a glass transition point (Tg) in the operating temperature region.

[0555] In selecting an appropriate base material, not only the magnitudeof dipole moment in the molecules and the operating temperature regionbut also usability, moldability, availability, temperature property,weatherability and price should be adequately considered.

[0556] According to the piezoelectric material of this invention, themoment activator mixed in the base material may be a plurality ofcompounds selected from ones containing a benzothiazyl or benzothiazylradical or ones containing a diphenylacrylate radical such asethyl-2-cyano-3,3-di-phenylacrylate

[0557] Preferably, 10 to 200 parts by weight of a moment activator ismixed in 100 parts by weight of a base material. If less than 10 partsby weight of a moment activator is mixed, the amount of dipole momentwill not be sufficiently increased, whereas if more than 200 parts byweight of a moment activator is mixed, the moment activator will beinsufficiently mixed with the base material and insufficient mechanicalintegrity will result.

[0558] To select an appropriate moment activator to be mixed in the basematerial, not only the magnitude of dipole moment but also themiscibility between the moment activator and the base material should beduly considered. The SP values of both should be close enough.

[0559] The magnitude of dipole moment is subject to the base materialand moment activator. The amount of dipole moment varies with theworking temperature. The magnitude of dipole moment is also affected bythe magnitude of energy transferred to the base material. Thus, the basematerial and moment activator should be appropriately selected so as toprovide the largest possible magnitude of dipole moment, considering theexpected temperature and magnitude of energy.

[0560] A filler such as mica scales, glass pieces, glass fibers, carbonfibers, calcium carbonate, barite, or precipitated barium sulfate can beadditionally blended in the base material to increase the mechanicalstrength of the piezoelectric material or to reduce the cost of theproduct. Preferably, 10 to 80% by weight of a filler is blended in thebase material. If less than 10% by weight is blended, the addition ofthe filler will not sufficiently improve the strength, whereas if morethan 80% by weight is blended, it will not be actually blended in thebase material and will reduce the strength of the piezoelectric product.

[0561] The piezoelectric material or product of the invention can bemanufactured by mixing such a base material and moment activator, andoptionally a filler, dispersant, or thickener as desired, and dispersingand mixing the mixture using a conventional melting and mixing apparatussuch as a dissolver, Banbury mixer, planetary mixer, grain mill, openkneader, or vacuum kneader.

[0562] As described above, the moment activator is mixed in the basematerial to significantly promote dipole moment to provide an excellentpiezoelectric property. The magnitude of dipole moment in thepiezoelectric material containing a moment activator is represented asthe difference in dielectric constant (∈′) between A and B shown in FIG.4. That is, the magnitude of dipole moment increases as the differencein dielectric constant (∈′) between A and B increases.

[0563]FIG. 4 is a graph showing a relationship between the dielectricconstant (∈′) and the dielectric loss factor (∈″). The relationshipbetween the dielectric constant (∈′) and the dielectric loss factor (∈″)is given as follows: Dielectric Loss Factor (∈″)=Dielectric Constant(∈′)×Dielectric Loss Tangent (tan δ).

[0564] Through research on piezoelectric materials, the inventors havefound that the energy absorption capability or piezoelectric capacitycan be improved by increasing the dielectric loss factor (∈″).

[0565] The inventors have also found that the piezoelectric material ofthe present invention provides an excellent piezoelectric property whenthe dielectric loss factor is 50 or larger at the frequency of 110 Hz.

[0566] Embodiment

[0567] Various embodiments of the present invention are provided below,along with conventional comparative examples or comparisons, embodyingvibration dampers, sound absorbers, impact absorbers, electromagneticwave dampers, vibration shields, and piezoelectric materials, preparedfrom the energy conversion composition of the present invention.

[0568] First, embodiments of the vibration damper of the presentinvention are explained. Sample sheets 1 mm thick were prepared from 0part by weight of DCHBSA in 100 parts by weight of acrylic rubber(AR-15, Japan Zeon Corporation) as Comparison 1. 10 parts by weight ofDCHBSA was blended in 100 parts by weight of said acrylic rubber asEmbodiment 1. They were made into sheets with kneading roll means set at160 C.

[0569] The sheets obtained according to Embodiment 1 and Comparison 1were measured for elastic tangent (tan δ) at various temperatures. Themeasurements of elastic tangent (tan δ) were provided using ReovibronDDV-25FP (Orientech Inc.). The results are shown in FIG. 5.

[0570] Next, 0 part by weight (Comparison 2), 10 parts by weight(Embodiment 2), 30 parts by weight (Embodiment 3), 50 parts by weight(Embodiment 4), and 70 parts by weight (Embodiment 5) of DCHBSA wererespectively mixed with NBR (202 S (35% by weight nitrile) manufacturedby Japan Synthetic Rubber Inc.) to provide sample sheets in the samemanner as for Embodiment 1.

[0571] The sheets according to Embodiments 2 to 5 and Comparison 2 weremeasured for elastic tangent (tan δ) at various temperatures in the samemanner as for Embodiment 1. The results are shown in FIG. 6.

[0572] Next, 0 part by weight (Comparison 3), 20 parts by weight(Embodiment 6), 30 parts by weight (Embodiment 7), 40 parts by weight(Embodiment 8), and 50 parts by weight (Embodiment 9) of DCHBSA wererespectively mixed with NBR (DN401 (15% by weight nitrile) manufacturedby Japan Zeon Inc.) to provide sample sheets in the same manner as forEmbodiment 1.

[0573] The sheets according to Embodiments 6 to 9 and Comparison 3 weremeasured for elastic tangent (tand) at various temperatures in the samemanner as for Embodiment 1. The results are shown in FIG. 7.

[0574] Next, 0 part by weight (Comparison 4), 30 parts by weight(Embodiment 10), 50 parts by weight (Embodiment 11), and 100 parts byweight (Embodiment 12) of DCHBSA were respectively mixed withchlorinated polyethylene (Elasrene 352NA manufactured by Showa DenkoInc.) to provide sample sheets in the same manner as for Embodiment 1.

[0575] The sheets according to Embodiments 10 to 12 and Comparison 4were measured for elastic tangent (tan δ) at various temperatures in thesame manner as for Embodiment 1. The results are shown in FIG. 8.

[0576] Next, 0 part by weight (Comparison 5), 20 parts by weight(Comparison 6), 30 parts by weight (Comparison 7), 40 parts by weight(Comparison 8), and 50 parts by weight (Comparison 9) of DCHBSA wererespectively mixed with isoprene rubber (2200 manufactured by Japan ZeonInc.) to provide sample sheets in the same manner as for Embodiment 1.

[0577] The sheets according to Comparisons 5 to 9 were measured forelastic tangent (tan δ) at various temperatures in the same manner asfor Embodiment 1. The results are shown in FIG. 9.

[0578] As is apparent from FIGS. 5 to 9, the vibration damping levels ofthe sample sheets according to Embodiments 1 to 12 significantlyincreased as compared with the elastic tangents (tan δ) of the samplesheets according to Comparisons 1 to 4. The peaks of the elastictangents (tan δ) of the sample sheets according to Embodiments 1 to 12all fall near the normal temperature zone, indicating that thesematerials have an excellent vibration-energy absorption capability inthe operation temperature region. In particular, the sheet according toEmbodiment 1 has an elastic tangent (tan δ) of more than 3 near 20 C.,indicating that this sheet is practically very useful.

[0579] Isoprene rubber (non-polarity polymer) with or without DCHBSAaccording to Comparisons 5 to 9 did not show improvement as seen fromthe respective elastic tangents (tan δ).

[0580] Next, embodiments of an unconstrained vibration damper of thepresent invention are explained. 65.0 parts by weight of mica scales(Clarite Mica 30 C. manufactured by Kurare Co., Ltd.), 13.0 parts byweight of DCHP, and 13.0 parts by weight of DCHBSA were mixed with 9parts by weight of polyvinyl chloride, and the mixture was fed andkneaded in roll means set at 160 C. The kneaded mixture was thensandwiched between molds and heated at 180 C. for 180 seconds. It wasthen pressed at 80 kgf/cm² for 30 seconds with press means to provide asheet 1 mm thick. The sheet was cut into test pieces of 67 mm×9 mm(Embodiment 13) for the measurement of loss factor.

[0581] 65.0 parts by weight of mica scales (Clarite Mica 30 C.), 10.4parts by weight of DCHP, 10.4 parts by weight of DCHBSA, and 5.2 partsby weight of ECDPA were mixed with 9 parts by weight of polyvinylchloride to prepare test pieces (Embodiment 14) in the same manner asfor Embodiment 1.

[0582] 50.0 parts by weight of mica scales (Clarite Mica 30 C.) wasadded to 50 parts by weight of polyvinyl chloride with a DOP addition toprepare test pieces (Comparison 10) in the same manner as for Embodiment1.

[0583] The test pieces according to Embodiments 13 and 14 and Comparison10 were measured for dielectric loss factor (∈″), loss factor (η), andelastic tangent (tan δ). The loss factor (η) and elastic tangent (tan δ)were measured with a dynamic viscoelasticity measuring and testingapparatus (Reovibron DDV-25FP) and the dielectric loss factor (∈″) wasmeasured using Impedance/Gain Phase Analyzer 4194A (Yokokawa HewlettPackard, Inc). Table 1 shows the results of the measurements of thedielectric tangent (tan δ), dielectric constant (∈′), and dielectricloss factor (∈″) of each test piece, and FIG. 10 shows the results ofthe measurements of the loss factor (η). TABLE 1 Dielectric DielectricConstant Dielectric Loss Test Piece Tangent (tan δ) (∈′) Factor (∈″)Embodiment 1 4.80 18.84 90.41 Embodiment 2 4.42 17.97 79.43 Comparison2.78 11.29 31.39

[0584] Table 1 and FIG. 10 show that the test pieces according toEmbodiments 13 and 14 exhibited a good vibration-energy absorptioncapability, that is, a loss factor (η) about five to seven times as highas that of Comparison 10, indicating that the vibration-energyabsorption capability of the unconstrained damping material according tothis invention is far superior to that of the conventional unconstraineddamping materials. Embodiments were comparable to constrainedconventional damping materials. In addition, the dielectric loss factors(∈″) of the test pieces according to Embodiments 14 and 13 exceeded 50.

[0585] Next, embodiments for the vibration damping paint of the presentinvention are explained. Damping paints each containing a momentactivator were each deposited on substrates (Table 2). Vibration dampinglayers formed on the substrates were respectively measured fordielectric loss factor (∈″), loss factor (η), and loss tangent (tan δ).

[0586] The dielectric loss factor (∈″), loss factor (h) and elastictangent (tan δ) were measured using the dynamic viscoelasticitymeasuring and testing apparatus (Reovibron DDV-25FP) and the dielectricloss factor (∈″) was measured with Impedance/Gain Phase Analyzer 4194A(Yokokawa Hewlett Packard, Inc). TABLE 2 Temperature 20 C. DielectricLoss Damping Layer Ratio η Tan δ Factor (∈″) EC818/DCHBSA 10/0  0.0640.062 33.19 9/1 0.061 0.062 32.55 (200 HK 71.7 wt %) 8/2 0.072 0.08540.26 7/3 0.139 0.124 46.70 6/4 0.107 0.111 43.03 5/5 0.115 0.097 59.62EC818/2HPMMB 9/1 0.070 0.050 34.44 7/3 0.055 0.045 23.62 (200 HK 71.7 wt%) 5/5 0.063 0.045 28.65 VN168/DCHBSA 10/0  0.036 0.021 24.31 9/1 0.0500.100 13.57 (200 HN 71.7 wt %) 7/3 0.025 0.041  9.80 5/5 — — —VN168/2HPMMB 9/1 0.035 0.040 22.38 7/3 0.030 0.021 13.24 (200 HK 71.7 wt%) 5/5 0.025 0.021  9.46

[0587] In Table 2, EC818 is an acrylic paint material manufactured byDainippon Ink Chemical Industry, Inc. (50% nonvolatile component).VN-168 is vinyl acetate/acrylic copolymer manufactured by Dainippon InkChemical Industry, Inc. (44.0 to 46.0% of nonvolatile component), and200HK is mica scales manufactured by Kurare Co., Ltd.

[0588] Next, the moment activators and mica scales shown in Table 3 weremixed in EC818 and VN-168 to produce vibration damping paints, whichwere respectively deposited on substrates. Vibration damping layers wereformed on the substrates and measured for loss factor (η). The resultsare given in FIGS. 11 to 14. The loss factor (η) was measured using thedynamic viscoelasticity measuring and testing apparatus (ReovibronDDV-25FP). TABLE 3 Damping Layer (% by weight) Sample No. (paintmaterial/moment activator/filler) 1 EC818/DCHBSA/Mica scales (200 HK)(28.3/0/71.7) 2 EC818/DCHBSA/Mica scales (200 HK) (25.5/2.8/71.7) 3EC818/DCHBSA/Mica scales (200 HK) (22.6/5.7/71.7) 4 EC818/DCHBSA/Micascales (200 HK) (19.8/8.5/71.7) 5 EC818/DCHBSA/Mica scales (200 HK)(17.0/11.3/71.7) 6 EC818/DCHBSA/Mica scales (200 HK) (14.15/14.15/71.7)7 EC818/2HPMMB/Mica scales (200 HK) (28.3/0/71.7) 8 EC818/2HPMMB/Micascales (200 HK) (25.5/2.8/71.7) 9 EC818/2HPMMB/Mica scales (200 HK)(19.8/8.5/71.7) 10  EC818/2HPMMB/Mica scales (200 HK) (14.15/14.15/71.7)11  VN168/DCHBSA/Mica scales (200 HK) 28.3/0/71.7) 12  VN168/DCHBSA/Micascales (200 HK) (25.5/2.8/71.7) 13  VN168/DCHBSA/Mica scales (200 HK)(19.8/8.5/71.7) 14  VN168/2HPMMB/Mica scales (200 HK) (28.3/0/71.7) 15 VN168/2HPMMB/Mica scales (200 HK) (25.5/2.8/71.7) 16  VN168/2HPMMB/Micascales (200 HK) (19.8/8.5/71.7) 17  VN168/2HPMMB/Mica scales (200 HK)(14.15/14.15/71.7)

[0589] In the following are given embodiments of the sound absorptivematerial of the present invention as shown in FIGS. 15 to 17. FIG. 15shows a sound absorptive sheet 30 formed by adding 100 parts by weightof DCHBSA to a vinyl chloride resin and processing the mixture into asheet 1 mm thick. FIG. 16 shows a sound absorptive sheet 40 formed byadding 100 parts by weight of DCHBSA to a vinyl chloride resin, spinningthe mixture to prepare sound absorptive short fibers 41 to beincorporated into a sheet. FIG. 17 shows an open-cell foam polyurethanemolding 50 with an addition of 100 parts by weight of DCHBSA.

[0590]FIG. 18 shows a sound absorptive sheet 30 of FIG. 15 disposed in aconventional sound absorber 60 comprising glass fibers 61. It waspossible with the present invention to make the sound absorber 60 verythin and to still damp low-frequency sound of 500 Hz or less, which wasnot possible with a conventional noise damping material.

[0591]FIG. 19 shows sound absorption fibers 41 contained in an open cellfoam polyurethane molding. FIGS. 20 and 21 respectively show a sheet ofpaper 70 and a fabric 80 comprising the sound absorptive fibers 41. Theyprovide an excellent sound absorption capability and can beadvantageously used as wall or floor materials.

[0592] The sound absorptive materials with and without a momentactivator in the resin matrix were tested. Table 4 shows the results.TABLE 4 Mixing Ration % Dynamic Tan δ No. Sample by weight 23 C. 1Chlorinated PE + DCHBSA 50/50 3.2 2 PVC + PVC(DOP) + NBR + 12/32/6/30/202.0 DCHP + Calcium Carbonate 3 PVC(DOP) + NBR + 68/12/20 0.6 CalciumCarbonate 4 PVC 100  0.01

[0593] These samples were measured for the sound absorption coefficientusing a vertical-incident-sound absorption coefficient measuringapparatus manufactured by B & K Inc. (JIS No. A1405). The results areshown in FIGS. 22 (Sample 1), 23 (Sample 2), 24 (Sample 3), and 25(Sample 4). Each sample had ø29 and was 200 μm thick having a 20 mm airlayer behind.

[0594] FIGS. 22 to 25 show that the sound absorption coefficient ofSample 4 consisting of only PVC was 0.1 to 0.3 between 1,000 Hz to 4,000Hz while it was much lower than 0.1 in the low frequency region of 1,000Hz or less, indicating that this sample does not sufficiently absorbsound energy. Sample 3, which contained no moment activator, exhibited amaximum sound absorption coefficient of 0.5 between 1,000 Hz and 2,000Hz, which is somewhat higher than that of Sample 4 but also indicatesthat the energy absorption coefficient of Sample 3 is insufficient below1,000 Hz.

[0595] On the contrary, Samples 1 and 2 exhibited a sound absorptioncoefficient of more than 0.3 between about 400 Hz and about 1,200 Hz,and it is noteworthy that Sample 1 had a maximum sound absorptioncoefficient of more than 0.9 and that Sample 2 had a maximum soundabsorption coefficient of more than 0.8.

[0596] In addition, the dynamic tand of each sample shown in Table 4 andthe sound absorption coefficient shown in FIGS. 22 to 25 show that thesound absorption coefficient increases as the dynamic tand increases.

[0597] Next, embodiments of the sound absorptive sheet of the presentinvention are explained. Paper (Tsumikusa paper P100-35; 12 g/m²)provided fibrous sound absorptive sheets (136 g/m²; 24 g/m² polymer), bymeans of immersing the paper in an emulsion of a polymer materialcomprising 100 parts by weight of DCHBSA and 100 parts by weight ofchlorinated polyethylene, and drying same (Embodiment 15).

[0598] The fibrous sheet of Embodiment 15 was also used as Comparison11.

[0599] Japan paper of 32 g/m² was used to provide fibrous soundabsorptive sheets (73 g/m²; 41 g/m²) by means of immersing the paper inan emulsion of a polymer material comprising 100 parts by weight ofDCHBSA and 100 parts by weight of chlorinated polyethylene, and dryingsame (Embodiment 16).

[0600] The fibrous sheet of Embodiment 16 was also used as Comparison12.

[0601] Silk fabric of 36 g/m² was used to provide fibrous soundabsorptive sheets (204 g/m²; 168 g/m² polymer) by means of immersing thefabric in an emulsion of a polymer material comprising 100 parts byweight of DCHBSA and 100 parts by weight of chlorinated polyethylene,and drying same (Embodiment 17).

[0602] The fibrous sheet of Embodiment 17 was also used as Comparison13.

[0603] The sound absorptive sheets according to Embodiments 15 to 17 andComparisons 11 to 13 were measured for dynamic loss tangent (tan δ),dielectric tangent (tan δ), dielectric loss factor (∈″) and dielectricconstant (∈′).

[0604] The results are shown in Table 5 and FIG. 26. TABLE 5 SoundAbsorptive Dielectric Dielectric Dielectric Sheet Tangent δ Constant(∈′) Loss Factor (∈″) Embodiment 15 5.43 1.86 10.11 Embodiment 16 5.11.4 7.3 Embodiment 17 5.1 4.4 22.4 Embodiment 11 4.57 0.22 0.99Embodiment 12 2.7 1.22 3.3 Embodiment 13 4.1 1.7 6.95

[0605] These sound absorptive sheets were measured for sound absorptioncoefficient using the vertical-incident-sound absorptive coefficientmeasuring apparatus manufactured by B & K Inc. (JIS No. A1405).

[0606] The results are shown in FIGS. 27 (Embodiment 15 and Comparison11), 28 (Embodiment 16 and Comparison 12), and 29 (Embodiment 17 andComparison 13). Each sample had ø29 and was 200 μm thick having a 20 mmair layer behind.

[0607] Next, embodiments of the foam sound absorptive material of thepresent invention are explained. DCHBSA was mixed in liquid A (PolyolMP-923 manufactured by Mitsui Toatsu Chemical, Inc.). The mixture waskneaded for five minutes using ceramic triple roller means.

[0608] Liquid B (Cosmonate MC-71 manufactured by Mitsui Toatsu Chemical,Inc.) was added to the kneaded mixture and stirred at a high speed forten seconds and then fed in a pipe 100 mm in diameter for foaming (roomtemperature). A cover was attached on the upper opening of the pipe toprevent the mixture from foaming over the volume of the pipe.

[0609] Liquids A and B were mixed at the weight ratio of 100 to 47.

[0610] The mixture of 100 parts by weight was respectively blended with30 parts by weight (Embodiment 18), 50 parts by weight (Embodiment 19),and 100 parts by weight (Embodiment 20) of DCHBSA to provide three typesof mixtures. They were adjusted to provide an expansion rate of 20 timesthe pipe volume.

[0611] The foamed moldings were cut into test pieces 20 mm thick. A testpiece containing no DCHBSA was also prepared as Comparison 14.

[0612] The sound absorptive sheets according to Embodiments 18 to 20 andComparison 14 were measured for dielectric tangent (tan δ), dielectricloss factor (∈″), and dielectric constant (c′). The results are shown inTable 6. TABLE 6 Sound Absorptive Dielectric Dielectric Dielectric LossMaterial Tangent δ Constant (∈′) Factor (∈″) Embodiment 18 0.98 9.919.71 Embodiment 19 1.11 11.40 12.66 Embodiment 20 1.58 24.77 39.10Comparison 14 0.81 6.68 5.41

[0613] These test pieces were measured for sound absorption coefficientusing the vertical-incident-sound absorption coefficient measuringapparatus manufactured by B & K Inc. (JIS No. A1405). The results areshown in FIG. 30.

[0614]FIG. 30 shows that when the frequency was lower than 2,000 Hz, thesound absorption coefficient of Comparison 14 rapidly decreased to halfthe coefficient between 1,000 Hz and 2,000 Hz. The figure also showsthat the sound absorption coefficient increased as the mixing amount ofDCHBSA increased (Embodiment 18 to 20). In particular, between 1,000 Hzand 2,000 Hz, the sound absorption coefficient of Embodiment 3 wasunexpectedly high, twice to 2.5 times that of Comparison 14.

[0615] Next, embodiments of the sound absorptive fibers of the presentinvention are explained. DCHBSA was mixed in chlorinated polyethyleneand the mixture as a fibrous material was fed in extrusion-spinningmeans. The mixing ratios (parts by weight) of chlorinated polyethyleneto DCHBSA were 100 to 0 (Comparison 15) and 100 to 100 (Embodiment 21).The diameter of a screw blade of the spinning machine was 25 mm, and thediameter of a nozzle was 1 mm. The temperature of the nozzle was 130 C.The extruded fibers were drawn to provide the diameter of 0.4 mm andthen cut to 40 mm long pieces.

[0616] These fibers were immersed and stirred in a container containinga water solution of 1% polyvinyl alcohol, and when the solution becameuniform, the water solution was drained and a 3-D test piece (non-wovencloth) of polyvinyl alcohol fabric was obtained on the mesh at thebottom of the container.

[0617] The test pieces of Embodiment 21 and Comparison 15 were measuredfor dielectric tangent (tan δ), dielectric loss factor (∈″), anddielectric constant (∈′). The results are shown in Table 7. TABLE 7Dielectric Dielectric Constant Dielectric Loss Test Piece Tangent δ (∈′)Factor (∈″) Embodiment 21 1.71 25.31 43.28 Embodiment 15 0.62 6.38 3.96

[0618] These test pieces were measured for sound absorption coefficient.The results are shown in FIG. 31. The sound absorption coefficient wasmeasured using the vertical-incident-sound absorption coefficientmeasuring apparatus manufactured by B & K Inc. (JIS No. A1405). Eachtest piece had a thickness of 20 mm and ø29 mm or ø100 mm.

[0619]FIG. 31 shows that the sound absorption coefficient of the testpiece according to Embodiment 21 consisting of sound absorptive fiberswhich comprise chlorinated polyethylene and DCHBSA as a moment activatoris 2 to 35% higher than that of the test piece of Comparison 15consisting of sound absorptive fibers which comprise chlorinatedpolyethylene without DCHBSA. There is a large difference between 2,000Hz and 6,300 Hz. This clearly shows that the mixture of DCHBSAsignificantly improves the sound absorption capability.

[0620] Next, embodiments of the impact absorptive material of thepresent invention are explained. FIG. 32 shows a shoe 90 where a bottomsurface 91 and a kneel portion 92 are formed by means of adding 100parts by weight of DCHBSA to a vinyl chloride resin. The shoe 90 whosebottom surface 91 and kneel portion 92 are composed of the impactabsorptive material of the invention provides excellent impactabsorption and can reduce fatigue of the wearer from a long walk.

[0621]FIG. 33 shows a plaster cast 100 comprising a non-woven clothlayer 102 consisting of fibers 101 formed by spinning a vinyl chlorideresin where 100 parts by weight of DCHBSA was added. When a force isapplied onto the plaster cast 100, the energy is absorbed by impactabsorptive fibers 101 which provide the non woven cloth layer 102,thereby reliably protecting the wearer's body portion from the impact.

[0622]FIGS. 34 and 35 respectively show a top cover of a saddle 110 anda handle grip 120 of a bicycle. The base material which canmagnificently damp shocks was provided by means of adding 100 parts byweight of DCHBSA to a vinyl chloride resin and molding the mixture.

[0623] Next, embodiments of another impact absorptive material of theinvention are explained. One hundred parts by weight of DCHBSA was mixedin 100 parts by weight of chlorinated polyethylene and the mixture wasmolded into cylinders with a diameter of 29.0 mm and thickness of 2, 3,5, 6, and 12.7 mm (Embodiment 22).

[0624] Urethane was used instead of chlorinated polyethylene, and as forEmbodiment 1 six cylinders with different diameters without DCHBSA wereprepared as Comparison 16. NBR was used instead of chlorinatedpolyethylene, and as for Embodiment 22 six cylinders with differentdiameters without DCHBSA were prepared as Comparison 17. BR was usedinstead of chlorinated polyethylene and as for Embodiment 22 sixcylinders with different diameters without DCHBSA were prepared asComparison 18. Acrylic resin was used instead of chlorinatedpolyethylene, and as for Embodiment 22 six cylinders with differentdiameters without DCHBSA were prepared as Comparison 19. Sorbosein wasused instead of chlorinated polyethylene, and as for Embodiment 22 sixcylinders with different diameters without DCHBSA were prepared asComparison 20. Each of these samples was measured for impact resiliencein accordance with the impact resilience test specified in JISK6301-1975. The results are shown in FIG. 36.

[0625] The test apparatus shown in FIGS. 37 to 40 was used to measurethe impact resilience. An iron bar was horizontally suspended with 4hanging threads, and its impact end was shaped semi-spherical with adiameter of 12.7 mm, the other end providing a pointer. The iron bar hada length of about 356 mm, diameter of 12.7 mm, and weight of 350 g. Thesuspension height of the iron bar was 2,000 mm and the drop height was100 mm.

[0626] The measurement scale of the testing apparatus had a horizontallength of 625 mm and the radius of 2,000 mm. The pointer was adjusted sothat when the iron bar was suspended it was placed at zero with itsimpact end contacting the surface of the test piece.

[0627] As shown in FIG. 36, the impact resilience of the impactabsorptive material according to Embodiment 22 was as low as about 2%,whereas the impact resilience of the impact absorptive materialaccording to Comparison 20 was about 8 to 18%. The impact resilience ofthe impact absorptive materials according to Comparisons 16 to 19 was ashigh as about 30 to 55%, indicating that these materials did not providesufficient impact absorption. Since the results of the tests show thatthe impact absorptive material of Embodiment 22 can provide excellentimpact absorption regardless of its thickness, the material can bepractically used in varied applications.

[0628] Next, 6 samples were prepared similarly with Embodiment 22 exceptthat 70 parts by weight for Embodiment 23, 50 parts by weight forEmbodiment 24, 30 parts by weight for Embodiment 25, and 0 part byweight for Comparison 21 of DCHBSA were blended within the samples. Eachsample was measured for impact resilience as for Embodiment 1.

[0629] The results are shown in FIG. 41 together with the results of themeasurement of the sample of Embodiment 22.

[0630] As shown in FIG. 41, the impact absorptive material according toComparison 21 containing no DCHBSA had an impact resilience of about 13to 26%, whereas the impact absorptive material according to Embodiment25 had an impact resilience of about 6 to 17%. The impact absorptivematerial according to Embodiment 24 had an impact resilience of about 4to 11%, the impact absorptive material according to Embodiment 23 had animpact resilience of about 3 to 8%, and the impact absorptive materialof Embodiment 22 had an impact resilience of about 2 to 3%, indicatingthat the impact damping capability improves as the amount of DCHBSAtherein increases. The capability improves from Embodiments 25 to 22 inthat order as the amount of DCHBSA increases in the same order, which isindependent of the thickness of the materials.

[0631] Next, embodiments of the impact absorptive material according tothis invention as applied onto front forks are explained. 50% by weightof DCHBSA was mixed in 50% by weight of chlorinated polyurethane (thetemperature of the sample was 22 C.) and the mixture was molded into acylinder having a diameter of 28 mm and a height of 30 mm. The cylinderhad grooves 14b in its circumference as shown in FIG. 42. This cylinderwas used as an impact absorber (Embodiment 26).

[0632] An impact absorber (Comparison 22) was formed by means of moldingas for Embodiment 26 except that an MCU elastomer (manufactured by TANGECORPORATION) was used.

[0633] An impact absorber (Comparison 23) was formed by means of moldingas for Embodiment 26 except that 100% by weight of chlorinatedpolyethylene was used.

[0634] An impact absorber (Comparison 24) was formed by means of moldingas for Embodiment 26 except that 100% by weight of NBR (hardness: 70)was used.

[0635] The impact absorbers according to Embodiment 26 and Comparison 22to 24 were measured for dielectric tangent (tan δ), dielectric lossfactor (∈″), and dielectric constant (∈′). The results are shown inTable 8. TABLE 8 Dielectric Dielectric Constant Dielectric Loss ImpactAbsorber Tangent δ (∈′) Factor (∈′) Embodiment 26 23.5 9.0 211.7Comparison 22 1.8 0.9 1.62 Comparison 23 17.1 3.4 58.14 Comparison 248.6 1.3 11.18

[0636] The impact absorbers were also subjected to an impact absorptiontest. As shown in FIG. 43, the test was conducted by installing theimpact absorbers 14 between the bottom of the outer tube 12 and thelower end of the inner tube 13, and dropping a 12-kg weight onto a plate24 on the outer tube 12 from a height of 50 mm. A vibration pickup 22(NP-601) attached to the inner tube 13 was used to measure the impact.An FFT analyzer 23 (Ono Instrument Inc.) was used to amplify the signalobtained. The results are shown in FIG. 44. For comparison, a front forkhaving no built-in impact absorber was also tested for impactabsorption. The test was conducted under ambient vibration of 44.80 dBand temperature of 17 C. The results of 50 tests were averaged.

[0637] As is apparent from FIG. 44, the vibration acceleration level ofthe front fork having no impact absorber was 65 to 70 dB, whereas thefront fork including the impact absorber according to Comparison 22 hada vibration acceleration level of 60 dB, that is, 5 to 10 dB lower thanthat of the front fork without impact absorber. The front fork havingthe built-in impact absorber according to Comparison 24 which comprisesNBR as its base material exhibited a vibration acceleration level of 63to 65 dB, and the front fork having the built-in impact absorberaccording to Comparison 23 which comprises chlorinated polyethylene asits base material exhibited a vibration acceleration level of 50 to 55dB, indicating that the impact was absorbed. Likewise, the front forkhaving the built-in impact absorber according to Embodiment 26 whichcomprises chlorinated polyethylene as its base material and DCHBSA had avibration acceleration level of 45 to 50 dB, that is, 15 to 20 dB lowerthan the front fork without absorber material and Comparison 22. Theseresults show that the impact absorber according to Embodiment 26provides excellent impact absorption, which is unexpectedly higher thanthose of conventional impact absorptive products.

[0638] Next, embodiments of the impact absorptive member according tothis invention as applied onto a grip tape are explained.

[0639] 50% by weight of DCHBCA was mixed in 50% by weight of chlorinatedpolyethylene (the temperature of the sample was 22-C.) and the mixturewas molded into a grip tape 1 mm thick, 25 mm wide, and 1,200 mm long(Embodiment 27).

[0640] Another grip tape was prepared as Comparison 25 as above exceptthat 100% by weight of chlorinated polyethylene was used.

[0641] Conventional Product 1

[0642] A grip tape wound round a tennis racket grip (Wilson Inc., “LadyUltra”)

[0643] Conventional Product 2

[0644] “G-296” manufactured by Dyack Inc. (NBR)

[0645] Conventional Product 3

[0646] “Wet Super Grip” (Yonex Inc.)

[0647] Conventional Product 4

[0648] “EXGRADE” over-grip (Prince Inc.)

[0649] Conventional Product 5

[0650] “Multi-Soft Grip Tape” (Mizuno Inc.)

[0651] The grip tapes according to Embodiment 27, Comparison 25, andConventional Products 1 to 5 were measured for dielectric tangent (tanδ), dielectric loss factor (∈″), and dielectric constant (∈′). Theresults are shown in Table 9. TABLE 9 Dielectric Dielectric ConstantDielectric Loss Grip Tape Tangent δ (∈′) Factor (∈″) Embodiment 27 9.0023.50 211.70 Comparison 25 3.40 17.10 58.14 Convention 1 1.30 8.60 11.18Convention 2 1.60 8.90 14.24 Convention 3 1.80 9.20 16.56 Convention 42.00 9.10 18.20 Convention 5 0.90 6.50 5.85

[0652] The grip tapes according to Embodiment 27, Comparison 25, andConventional Products 1 to 5 were subjected to an impact absorptiontest. As shown in FIGS. 45 and 46, a tennis racket 20 manufactured byWilson Inc. (“Lady Ultra”), having a grip tape wound round its grip endwas placed on a base 21 and fixed by bolt and plate means 22.

[0653] A vibration acceleration pickup (NP-601) 24 connected to an FFTanalyzer (Ono Instrument Inc.) 23 was mounted on the plate 22.

[0654] A tennis ball 25 was dropped onto the net of the racket 20 from aheight of 1 m, and the vibration acceleration level (dB) was measuredusing the vibration acceleration pickup 24 to provide measurement of theimpact vibration generated on the plate 22. The FF1 analyzer 23 (OnoInstrument Inc.) was used to amplify the signal. The results of themeasurement are shown in FIG. 47. During the measurement, thetemperature was 20 C. and the ambient vibration was 49.20 dB. Theresults are shown in FIG. 47 (average of 50 measurements). Forcomparison, a grip without a grip tape was prepared and also subjectedto an impact absorption test.

[0655] As is apparent from FIG. 47, the vibration acceleration level ofthe grip end without a tape was 68 to 70 dB, whereas the vibrationacceleration level of the Conventional Product 5 was 66 to 68 dB, onlyabout 2 dB lower than the grip end without a tape. Conventional Products1 to 4 and Comparison 25 exhibited a vibration acceleration level of 60to 65 dB, which was considerably lower than that of the grip end withouta tape. On the other hand, the grip end according to Embodiment 27exhibited a vibration acceleration level of 56 to 57 dB, which was 11 to14 dB lower than that of the grip end without a tape, indicating thatEmbodiment 27 has an excellent impact absorption capability.

[0656] Next, embodiments of the impact absorptive material according tothis invention as applied onto a shoe sole are explained.

[0657] 50% by weight of DCHBSA was mixed in 50% by weight of chlorinatedpolyethylene (the temperature of the sample was 22 C.) and the mixturewas molded into plates 1 mm thick (Embodiment 28), 3 mm thick(Embodiment 29), 5 mm thick (Embodiment 30), and 10 mm thick (Embodiment31).

[0658] Additional plates 1 mm thick (Comparison 26), 3 mm thick(comparison 27), 5 mm thick (Comparison 28), and 10 mm thick (Comparison29) were also prepared as for the Embodiments except that 100% by weightof chlorinated polyethylene was used.

[0659] Conventional product (heel pad, plate 4 mm thick, Impulse Inc.)(Comparison 30).

[0660] Conventional product (gel, plate 4 mm thick, Impulse Inc.)(Comparison 31).

[0661] Conventional product (air, plate 10 mm thick, Impulse Inc.)(Comparison 32).

[0662] Conventional product (sports gel, plate 3 mm thick, Wilson Inc.)(Comparison 33).

[0663] Those impact absorbers according to Embodiment 28 and Comparisons26 and 30 to 33 were measured for dielectric tangent (tan δ), dielectricloss factor (∈″), and dielectric constant (∈′). The results are shown inTable 10. TABLE 10 Dielectric Dielectric Constant Dielectric Loss ImpactAbsorber Tangent δ (∈′) Factor (∈″) Embodiment 28 9.0 23.50 211.70Comparison 26 3.4 17.10 58.14 Comparison 30 0.5 1.70 0.85 Comparison 310.6 2.20 1.32 Comparison 32 0.5 1.30 0.65 Comparison 33 1.1 1.90 2.09

[0664] The impact absorbers according to Embodiments 28 to 31 andComparisons 26 to 33 were subjected to an impact absorption test. Asshown in FIG. 48, the test was conducted by placing each impact absorber1 on a base 20, dropping a 12-kg weight 21 onto the base 20 from aheight of 250 mm, using a vibration pickup 23 (NP-601) connected to theweight 21 to measure the impact acceleration level (dB), and using anFFT analyzer 22 (Ono Instrument Inc.) to amplify the signal. The resultsof the test are shown in FIG. 49. During the measurement, thetemperature was 20 C. and the ambient vibration was 49.56 dB. Theresults are shown in FIG. 49 as the average of 50 measurements. Forcomparison, a shoe sole without any impact absorber was also preparedand subjected to an impact absorption test.

[0665] As is apparent from FIG. 49, the vibration acceleration level ofthe device without an impact absorber was about 73 dB, and the impactabsorption capability of the Comparisons was gradually improved as thethickness of the impact absorbers increased. The vibration accelerationlevel of Comparison 26 comprising chlorinated polyethylene as its basematerial was 80 dB. The levels were respectively 69, 65 and 61 dB fromComparisons 27 to 29. In addition, Comparisons 30 to 33 all exhibited avibration level of 55 to 65 dB, whereas the damping capability increasedfrom Embodiment 29 to Embodiment 31 where the thickness increases inthis order, with an exception of Embodiment 1 whose thickness is 1 mm.In particular, Embodiment 31 with a thickness of 10 mm exhibited anexcellent damping property of 52 to 53 dB.

[0666] As shown in FIG. 50, each of the impact absorbers 1 according toEmbodiments 28 to 31 and Comparisons 26 to 33 was placed in a safetyshoe 24 (JIS product) and the vibration acceleration level was measuredas described above. The results are shown in FIG. 51. For comparison, asafety shoe without impact absorber was prepared and also subjected toan impact absorption test.

[0667] As is apparent from FIG. 51, the vibration acceleration level ofthe device without an impact absorber was about 65 dB, and the impactabsorption capability of the Comparisons was gradually improved as thethickness of the impact absorbers increased. The vibration accelerationlevel of Comparison 26 comprising chlorinated polyethylene as its basematerial was 64 dB, and Comparisons 27 to 29 (the thickness increasingin this order) exhibited a vibration acceleration level of 60, 59, and54 dB, respectively.

[0668] Comparisons 30 to 32 using conventional products exhibited avibration level of 55 to 57 dB and Comparison 33 exhibited a level of 52dB, whereas, with an exception of Embodiment 28 with a thickness of 1mm, the damping capability improved from Embodiment 29 to Embodiment 31(50 to 55 dB) whose thickness increased in this order.

[0669] In particular, Embodiment 31 with a thickness of 10 mm exhibiteda very excellent level of 50 to 52 dB.

[0670] Next, embodiments of the electromagnetic wave absorptive materialaccording to this invention are explained.

[0671] DCHBSA was mixed in chlorinated polyethylene, and the mixture waskneaded and molded between rollers into a sheet 1 mm thick. The sheetwas cut into 200 mm×200 mm pieces, which were used as test pieces.

[0672] The mixing ratio (parts by weight) of chlorinated polyethylene toDCHBSA was 100 to 0 (Comparison 34), 100 to 30 (Embodiment 32), 100 to50 (Embodiment 33), 100 to 70 (Embodiment 34), and 100 to 100(Embodiment 35).

[0673] The test pieces according to Embodiments 32 to 35 and Comparison34 were measured for dielectric tangent (tan δ), dielectric loss factor(∈″), and dielectric constant (∈′). The results are shown in Table 11.TABLE 11 Electromagnetic Dielectric Dielectric Loss Absorber DielectricTangent σ Constant (ε′) Factor (ε″) Embodiment 32 5.2 22.1 115.0Embodiment 33 5.7 29.1 164.7 Embodiment 34 6.9 25.8 178.0 Embodiment 359.0 23.5 211.7 Comparison 34 3.4 17.1 58.9

[0674] These test pieces were measured for electromagnetic waveabsorption capability (db). The results are shown in FIG. 52. Theelectromagnetic wave absorption capability electromagnetic shiedevaluating apparatus (TR-17301 manufactured by Advantest Inc.). Electricfields of 10 to 1,000 MHz were used in the test.

[0675] Embodiments of the electromagnetic wave absorptive paintcomprising the electromagnetic wave absorptive material according tothis invention are described below. A mixture of chlorinatedpolyethylene and DCHBSA was dispersed in water to provide an emulsion,which was deposited on a surface of a substrate using an air spray gun.

[0676] An electromagnetic wave absorptive layer was provided. This layerwas measured for dielectric tangent (tan δ), dielectric loss factor(∈″), and dielectric constant (∈′). The results are shown in FIG. 12.

[0677] The mixing ratio (parts by weight) of chlorinated polyethylene toDCHBSA was 100 to 0 (Comparison 35), 100 to 30 (Embodiment 36), 100 to50 (Embodiment 37), 100 to 70 (Embodiment 38), and 100 to 100(Embodiment 39). TABLE 12 Electromagnetic Dielectric Dielectric ConstantDielectric Loss Absorptive Layer Tangent σ (ε′) Factor (ε″) Embodiment36 5.2 22.1 115.0 Embodiment 37 5.7 29.1 164.7 Embodiment 38 6.9 25.8178.0 Embodiment 39 9.0 23.5 211.7 Comparison 35 3.4 17.1 58.9

[0678] These electromagnetic wave absorption layers were measured forelectromagnetic wave absorption capability (db). The results are shownin FIG. 53. The electromagnetic wave absorption capability (db) wasmeasured using the electromagnetic shied evaluating apparatus (TR-17301manufactured by Advantest, Inc.). Electric fields of 10 to 1,000 MHzwere used in the test.

[0679] Next, embodiments of the vibration-proofing material according tothis invention are described. Tables 13-1 and 13-2 show thecompositions, dielectric properties, mechanical properties, and dampingratios. The dielectric loss factor (∈″) shown in Tables 13-1 and 13-2was measured with Impedance/Gain Phase Analyzer 4194A, a measuringapparatus manufactured by Yokokawa Hewlette Packard, Inc. and theelastic tangent (tan δ) was measured using Reovibron DDV-25FP, ameasuring apparatus manufactured by Orientech, Inc. The damping ratio(ξ) is tand/2, so it was simply provided by dividing the elastic tangent(tan δ) by 2.

[0680] The measurement was made at 20, 40, or 60-C. The frequency was110 Hz and the T/P size was ø20×t 1.0 mm. TABLE 13-1 Damp- ing VibrationShield Dielectric (110 Moment Temp Property (110 Hz) Mech. Hz) Base ActMix (C.) ε′ Tan δ ε″ Tan δ ξ 20 6.1 2.1 12.8 0.01 0.005 40 7.6 2.1 16.00.02 0.010 60 8.0 2.5 20.0 0.03 0.015 DCHP 100 20 13.7 1.8 24.7 0.250.125 peak phr 40 41.2 3.4 140.1 2.00 1.000 50 C. 60 37.3 3.2 119.4 1.800.900 DCHBSA 100 20 12.4 1.3 16.1 0.01 0.005 PVC peak phr 40 8.2 2.318.9 0.02 0.010 Tand 80 C. 60 9.8 3.2 31.4 0.55 0.275 2HPMMB 100 20 11.91.1 13.1 0.01 0.005 peak peak phr 40 7.1 2.0 14.2 0.01 0.005 105 100 C.60 7.6 2.1 16.0 0.02 0.010 C DDP 100 20 11.7 1.8 21.1 0.23 0.115 peakphr 40 36.4 3.4 123.8 1.95 0.975 50 C. 60 16.8 3.6 60.5 1.20 0.600 CBS100 20 10.2 1.8 18.4 0.20 0.100 peak phr 40 28.8 3.7 106.6 1.65 0.825 50C. 60 18.1 5.3 95.9 1.40 0.700 BBS 100 20 5.9 1.7 10.0 0.15 0.075 peakphr 40 29.4 3.7 108.8 1.50 0.750 50 C. 60 32.6 4.0 130.4 1.85 0.925 MBTS100 20 4.1 2.0 8.2 0.10 0.050 peak phr 40 18.2 3.7 67.3 1.00 0.500 50 C.60 25.1 3.9 97.9 1.05 0.525 ECDPA 100 20 9.5 2.0 19.0 0.30 0.150 phr 4037.9 3.5 132.7 2.05 1.025 60 19.9 5.1 101.5 1.20 0.600

[0681] TABLE 13-2 Dielectric Damping Vibration Shield Property (110 Hz)Mech. (110 Hz) Base Moment Act Mix Temp. (C.) ε′ Tan δ ε″ Tan δ ξ —DCHBSA — — — — — — — Chlo peak 0 phr 20 17.1 3.4 58.9 1.00 0.500 .PE 15C. 30 phr — 22.1 5.2 115.0 1.50 0.750 Peak 18 C. 50 phr — 29.1 5.7 164.72.00 1.000 10 C. 23 C. 100 phr — 23.5 9.0 211.7 2.70 1.350 — — — — — — —— — — DCHBSA — — — — — — — NBR peak 0 wt % 20 6.1 1.8 10.7 0.09 0.045 AN−22 C. 20 wt % — 8.6 1.9 16.6 0.10 0.050 15% −18 C. 30 wt % — 10.7 3.133.1 0.40 0.200 Peak −10 C. 40 wt % — 16.5 3.3 55.0 0.60 0.300 −30 −5 C.50 wt % — 15.1 2.4 36.7 0.50 0.250 C. — — — — — — — — — DCHBSA — — — — —— — NBR peak 0 phr 20 14.3 3.4 48.3 0.80 0.400 AN 3 C. 10 phr — 21.1 3.471.5 1.00 0.500 35% 8 C. 30 phr — 21.8 4.5 98.0 1.40 0.700 Peak 10 C. 50phr — 22.2 6.6 146.6 1.80 0.900 0 C. 13 C. 70 phr — 22.6 9.6 216.9 3.001.500 — — — — — — — — — — DCHBSA — — — — — — — NBR Peak 0 phr 20 54.32.7 146.2 1.60 0.800 AN 17 C. 10 phr 27.0 6.0 162.9 1.80 0.900 45% 19 C.30 phr 27.9 7.6 212.5 2.40 1.200 Peak — — — — — — — — 15 C. — — — — — —— — — — — — — — — — — — DCHBSA — — — — — — — ACR Peak 0 phr 20 18.3 9.6175.3 2.50 1.250 Peak 15 C. 10 phr — 19.9 11.3 244.5 2.90 1.450 15 C. 15C. 30 phr — 19.2 6.0 114.9 1.80 0.900

[0682] Next, embodiments of the piezoelectric material according to thisinvention are described.

[0683] One hundred parts by weight of DCHBSA was mixed in 100 parts byweight of polyvinyl chloride (the sample temperature was 22 C.) and themixture was molded into a plate with a thickness of 1 mm and dimension150×50 mm. An electrode of silver paste (Asahi Chemical Research, Inc.,LS-506J, 140×40 mm) was formed on both surfaces of the plate to preparea sample (Embodiment 40).

[0684] A sample (Embodiment 41) was prepared as for Embodiment 40 exceptthat 100 parts by weight of 2HPMMB was blended in 100 parts by weight ofpolyvinyl chloride.

[0685] A sample (Embodiment 42) was prepared as for Embodiment 40 exceptthat 100 parts by weight of ECDPA was blended in 100 parts by weight ofpolyvinyl chloride.

[0686] A sample (Comparison 36) was prepared as for Embodiment 40 usingonly polyvinyl chloride.

[0687] These samples according to Embodiments 40 to 42 and Comparison 36Sample were measured for dielectric tangent (tan δ), dielectric lossfactor (∈″), and dielectric constant (∈′). The results are shown inTable 14. The dielectric tangent (tan δ), dielectric loss factor (∈″),and dielectric constant (∈′) were measured at the glass transition pointof each sample. TABLE 14 Dielectric Dielectric Dielectric Sample Tangentσ Constant (ε′) Loss Factor (ε″) Embodiment 40 3.3 39.1 129.0 Embodiment41 3.9 40.6 158.3 Embodiment 42 3.5 37.9 132.7 Comparison 36 2.1 6.112.8

[0688] The samples according to Embodiments 40 to 42 and Comparison 36were measured for piezoelectric capability. The measurement was made byelectrically connecting the electrodes on the respective surfaces of thesample 11 to a voltmeter 12, placing the sample on a base 10, droppingan iron ball 13 (diameter: 20 mm; weight: 32.6 g) onto the sample 11from a height of 200 mm, and reading from the voltmeter 12 the maximumvoltage generated in the sample 11 (FIG. 54). This procedure wasrepeated five times to obtain the averages of the results, which areshown in Table 15. For comparison, the samples according to Embodiments40 to 42 and Comparison 36 were polarized and measured for piezoelectriccapability in the same manner. The polarization was carried out byapplying a 1-kV direct current to each sample in an oil bath at 100 C.for 1 hour and leaving the sample until the temperature of the bathbecame the room temperature. TABLE 15 Generated Voltage (mV) Sample NoPolarization Polarization Comparison 36 1.36 1.88 Embodiment 40 88.7490.78 Embodiment 41 114.04 141.22 Embodiment 42 112.58 113.81

[0689] Table 15 shows that Comparison 36 exhibited a low value, 1.36 or1.88 mV regardless of polarization treatment, whereas Embodiments 40 to42 without polarization exhibited an extraordinarily high value, about90 to 110 mV. The value of polarized Embodiment 41 was about 70 times ashigh as that of polarized Comparison 36, indicating that the momentactivator such as DCHBSA or 2HPMMB substantially contributed to theimprovement of the piezoelectric capability.

[0690]FIG. 55 shows pellets formed by adding 100 parts by weight ofDCHBSA to vinyl chloride resin and molding the mixture. These pellets120 can be melt spun to provide endothermic fibers.

[0691]FIG. 56 shows a tank of an earthquake-proof apparatus and aviscous fluid filled in the tank. This viscous fluid comprisedethyleneglycol where 100 parts by weight of DCHBSA was blended.

[0692] A smaller amount of this viscous fluid was able to provide thesame earthquake-proof effect as a larger amount of viscous fluid withoutDCHBSA.

[0693] A high-latent-heat medium that can be advantageously used intransmission cooling liquids, engine coolants, or mold cooling liquidswas produced by adding 100 parts by weight of DCHBSA to ethyleneglycol.

[0694] This high-latent-heat medium has a latent heat similar to that ofwater and is resistant to rusting. The medium provides an excellentcooling effect. The use of this medium can significantly reduce the sizeof a cooling apparatus such as a radiator.

1. A method of energy conversion comprising: applying energy to anenergy conversion material comprising a base material and a momentactivator, wherein said energy conversion material has dipoles in astable state; displacing the dipoles to an unstable state; and returningthe dipoles to a stable state.
 2. The method of claim 1, wherein thebase material comprises a polymer selected from the group consisting ofpolyvinyl chloride, acrylic rubber, acrylonitrile-butadiene rubber,styrene-butadiene rubber, chloroprene rubber, butadiene rubber, naturalrubber, isoprene rubber, and chlorinated polyethylene.
 3. The method ofclaim 1, wherein the base material comprises: a polymer selected fromthe group consisting of polyvinyl chloride, polyethylene, polypropylene,ethylene-vinyl acetate copolymer, polymethyl methacrylate,polyvinylidene fluoride, polyisoprene, polystyrene,styrene-butadiene-acrylonitrile copolymer, and styrene-acrylonitrilecopolymer; and a plasticizer.
 4. The method of claim 1, wherein themoment activator is a compound having a benzothiazyl, benzotriazyl, or adiphenyl acrylate radical.
 5. The method of claim 4, wherein the momentactivator comprises a compound selected from the group consisting ofN,N-dicyclohexylbenzothiazyl-2-sulfonamide (DCHBSA),2-mercaptobenzothiazole (MBT), dibenzothiazylsulfide (MBTS),N-cyclohexylbenzothiazyl-2-sulfenamide (CBS),N-tert-butylbenzpthiazyl-2-sulfenamide (BBS),N-oxydiethylenebenzothiazyl-2-sulfonamide (OBS), orN,N-diisopropylbenzothiazyl-2-sulfenamide (DPBS),2-(2′-hydroxy-3′-(3″,4″,5″,6″tetrahydrophthalimidemethyl)-5′-methylphenyl)-benzotriazole(2HPMMB), 2-2′-hydroxy-5′methylphenyl)-benzotriazole (2HMPB),2-(2′-hydroxy-3′-t-butyl-5′-methylphenyl)-5-chlorobenzotriazole(2HBMPCB), 2-(2′-hydroxy-3′,5′-di-t-butylphenyl)-5-chlorobenzotriazole(2HDBPCB), and ethyl-2-cyano-3,3-di-phenylacrylate.
 6. The method ofclaim 5, wherein the moment activator is a compound selected from thegroup consisting of N,N-dicyclohexylbenzothiazyl-2-sulfonamide (DCHBSA),N-cyclohexylbenzothiazyl-2-sulfenamide (CBS),2-(2′-hydroxy-3′-(3″,4″,5″,6″tetrahydrophthalimidemethyl)-5′-methylphenyl)-benzotriazole(2HPMMB), and ethyl-2-cyano-3,3-di-phenylacrylate.
 7. The method ofclaim 1, wherein the moment activator is present in an amount of 10 to500 parts by weight per 100 parts by weight of the base material.
 8. Themethod of claim 1, wherein the energy conversion material furthercomprises filler.
 9. The method of claim 8, wherein the filler comprisesmica scales, glass pieces, carbon fibers, calcium carbonate, barite, andprecipitated barium sulfate.
 10. The method of claim 8, wherein thefiller is present in an amount of 10 to 500 parts by weight per 100parts by weight of the base material.
 11. The method of claim 10,wherein the filler is present in an amount of 20 to 80 parts by weight.12. The method of claim 1, wherein the energy conversion material is anunconstrained vibration damper.
 13. The method of claim 1, wherein theenergy conversion material is a vibration damping paint.
 14. The methodof claim 13, wherein the moment activator is present in an amount of 10to 100 parts by weight per 100 parts by weight of the base material. 15.The method of claim 13, wherein the vibration damping paint furthercomprises an additive selected from the group consisting of dispersingagents, wetting agents, thickeners, antifoaming agents, and colorants.16. The method of claim 13 further comprising applying the vibrationdamping paint to a surface by an air spray gun, airless spray gun, orbrush.
 17. The method of claim 1, wherein the energy is sound energy andthe energy conversion material is a sound absorptive material.
 18. Themethod of claim 17, wherein the base material comprises a polymerselected from the group consisting of polyvinyl chloride, polyethylene,polypropylene, ethylene-vinyl acetate copolymer, polymethylmethacrylate, polyvinylidene fluoride, polyisoprene, polystyrene,styrene-butadiene-acrylonitrile copolymer, styrene-acrylonitrilecopolymer, polyester, polyurethane, polyamide, polyvinylidene,polyacrylonitrile, polyvinylalcohol, cellulose, acrylonitrile-butadienerubber, styrene-butadiene rubber, butadiene rubber, natural rubber,isoprene rubber, chlorinated polyethylene and chloroprene rubber. 19.The method of claim 17, wherein the moment activator is present in anamount of 10 to 430 parts by weight per 100 parts by weight of the basematerial.
 20. The method of claim 17, wherein the sound absorptivematerial further comprises corrosion inhibitor.
 21. The method of claim17, wherein the sound energy has a frequency of 1,000 Hz or less. 22.The method of claim 21, wherein the sound energy has a frequency of 500Hz or less.
 23. The method of claim 17, wherein the sound absorptivematerial is foamed or unfoamed and further comprises a form selectedfrom the group consisting of sheet, film, fiber, and block.
 24. Themethod of claim 17, wherein the sound absorptive material is disposedadjacent to a fiber surface.
 25. The method of claim 1, wherein theenergy conversion material is an impact absorptive material.
 26. Themethod of claim 25, wherein the moment activator is present in an amountof 10 to 200 parts by weight per 100 parts by weight of the basematerial.
 27. The method of claim 25, wherein the impact absorptivematerial is foamed or unfoamed and further comprises a form selectedfrom the group consisting of sheet, film, fibers, front fork, tape, andblocks.
 28. The method of claim 25, wherein the impact absorptivematerial is incorporated into a shoe sole.
 29. The method of claim 1,wherein the energy is electromagnetic energy and the energy conversionmaterial is an electromagnetic wave absorptive material.
 30. The methodof claim 29, wherein the electromagnetic energy has a frequency of 500to 2,000 MHz.
 31. The method of claim 29, wherein the moment activatoris present in an amount of 10 to 200 parts by weight per 100 parts byweight of the base material.
 32. The method of claim 29, wherein theelectromagnetic wave absorptive material is foamed or unfoamed andfurther comprises a form selected from the group consisting of paint,sheet, film, fibers, and blocks.
 33. The method of claim 1, wherein theenergy conversion material is a piezoelectric material.
 34. The methodof claim 33, wherein the moment activator is present in an amount in therange of 10 to 200 parts by weight per 100 parts by weight of the basematerial.
 35. The method of claim 1, wherein said energy is selectedfrom the group consisting of vibrational energy, sound energy, impactenergy, and electromagnetic energy.
 36. A method of vibration dampingcomprising: applying vibrational energy to a vibration damping materialcomprising acrylic rubber and a moment activator comprisingN,N-dicyclohexylbenzothiazyl-2-sulfonamide (DCHBSA), wherein saidvibration damping material has dipoles in a stable state; displacing thedipoles to an unstable state; and returning the dipoles to a stablestate.